feat: adds community docs back and best practices (#58)

# What 💻 
* Adds community docs back and best practices
* removes outdates oracle 

# Why ✋
* Important info to keep
* does not exist anymore 

# Evidence 📷
Include screenshots, screen recordings, or `console` output here
demonstrating that your changes work as intended

<!-- All sections below are optional. You can uncomment any section
applicable to your Pull Request. -->

<!-- # Notes 📝
* Any notes/thoughts that the reviewers should know prior to reviewing
the code? -->

content/00.build/65.developer-reference/25..best-practices.md

@@ -0,0 +1,121 @@
+---
+title: Security and best practices
+description:
+---
+
+Before diving into development on ZKsync Era, it's crucial to consider the following recommendations. These best
+practices will help you optimize your code, ensure security, and align with the unique characteristics of ZKsync Era.
+
+## Use `call` over `.send` or `.transfer`
+
+Avoid using `payable(addr).send(x)`/`payable(addr).transfer(x)` because the 2300 gas stipend may not be enough
+for such calls, especially if it involves state changes that require a large amount of L2 gas for data. Instead, we recommend using `call`.
+
+Instead of:
+
+```solidity
+payable(addr).send(x) // or
+payable(addr).transfer(x)
+```
+
+Use:
+
+```solidity
+(bool s, ) = addr.call{value: x}("");
+require(s);
+```
+
+This converts the `send`/`transfer` functionality to `call` and [avoids potential security risks outlined here.](https://consensys.net/diligence/blog/2019/09/stop-using-soliditys-transfer-now/).
+
+While `.call` offers more flexibility compared to `.send` or `.transfer`, developers should be aware that `.call`
+does not provide the same level of reentrancy protection as `.transfer`/`.send`. It's crucial to adhere to best
+practices like the checks-effects-interactions pattern and/or use reentrancy guard protection to secure your
+contracts against reentrancy attacks. It can help ensure the robustness and security of your smart contracts on the ZKSync VM, even under unexpected conditions.
+
+## Use the proxy pattern at the early stage of the protocol
+
+ZKsync Era is based on the zk-friendly VM. Thus, we offer
+[a dedicated compiler](/zk-stack/components/compiler/toolchain/overview)
+responsible for transforming conventional Solidity and Vyper code into zkEVM bytecode.
+
+While we have extensive test coverage to ensure EVM compatibility, issues may still appear.
+We will implement the patches for these in a timely manner.
+
+To integrate a compiler bug fix, you need to recompile and upgrade your smart contract. We recommend using the
+Proxy pattern for a few months after your first deployment on ZKsync Era, even if you plan to migrate to an immutable
+contract in the future.
+
+## Do not rely on EVM gas logic
+
+ZKsync Era has a distinctive gas logic compared to Ethereum. There are two main drivers:
+
+- We have a state-diff-based data availability, which means that the price for the execution depends on the L1 gas price.
+- ZKsync VM has a different set of computational trade-offs compared to the standard computational model. In
+practice, this means that the price for opcodes is different to Ethereum. Also, zkEVM contains a different set of
+opcodes under the hood and so the “gas” metric of the same set of operations may be different on ZKsync Era and on Ethereum.
+
+::callout{icon="i-heroicons-exclamation-triangle" color="amber"}
+Our fee model is being constantly improved and so it is highly recommended **NOT** to hardcode any constants since the fee
+model changes in the future might be breaking for this constant.
+::
+
+## `gasPerPubdataByte` should be taken into account in development
+
+Due to the state diff-based fee model of ZKsync Era, every transaction includes a constant called `gasPerPubdataByte`.
+
+Presently, the operator has control over this value. However, in EIP712 transactions, users also sign an upper bound
+on this value, but the operator is free to choose any value up to that upper bound. Note, that even if the value
+is chosen by the protocol, it still fluctuates based on the L1 gas price. Therefore, relying solely on gas is inadequate.
+
+A notable example is a Gnosis Safe’s `execTransaction` method:
+
+```solidity
+// We require some gas to emit the events (at least 2500) after the execution and some to perform code until the execution (500)
+// We also include the 1/64 in the check that is not send along with a call to counteract potential shortcomings because of EIP-150
+require(gasleft() >= ((safeTxGas * 64) / 63).max(safeTxGas + 2500) + 500, "GS010");
+// Use scope here to limit variable lifetime and prevent `stack too deep` errors
+{
+    uint256 gasUsed = gasleft();
+    // If the gasPrice is 0 we assume that nearly all available gas can be used (it is always more than safeTxGas)
+    // We only subtract 2500 (compared to the 3000 before) to ensure that the amount passed is still higher than safeTxGas
+    success = execute(to, value, data, operation, gasPrice == 0 ? (gasleft() - 2500) : safeTxGas);
+    gasUsed = gasUsed.sub(gasleft());
+
+    // ...
+}
+```
+
+While the contract does enforce the correct `gasleft()`, it does not enforce the correct `gasPerPubdata`, since there
+was no such parameter on Ethereum. This means that a malicious user could call this wallet when the `gasPerPubdata` is
+high and make the transaction fail, hence making it spend artificially more gas than required.
+
+This is the case for all relayer-like logic ported directly from Ethereum and so if you see your code relying on logic
+like “the user should provide at X gas”, then the `gasPerPubdata` should be also taken into account on ZKsync Era.
+
+For now, ZKsync Era operators use honest values for ETH L1 price and `gasPerPubdata`, so it should not be an issue if
+enough margin is added to the estimated gas. In order to prepare for the future decentralization of ZKsync Era,
+it is imperative that you update your contract.
+
+## Use native account abstraction over `ecrecover` for validation
+
+Use ZKsync Era's native account abstraction support for signature validation instead of this function.
+
+We recommend not relying on the fact that an account has an ECDSA private key, since the account may be governed by
+multisig and use another signature scheme.
+
+Read more about [ZKsync Era Account Abstraction support](/build/developer-reference/account-abstraction/introduction).
+
+## Use local testing environment
+
+For optimal development and testing of your contracts, it is highly recommended to perform local testing before deploying
+them to the mainnet. Local testing allows you to test your contracts in a controlled environment, providing benefits such as
+reduced network latency and cost.
+
+We provide [two different testing environments](/build/test-and-debug) designed for local testing purposes.
+These tools allow you to simulate the ZKsync network locally, enabling you to validate your contracts effectively.
+
+By incorporating local testing into your development workflow, you can effectively verify the behavior and functionality of
+your contracts in a controlled environment, ensuring a smooth deployment process to the mainnet.
+
+For detailed instructions on configuring the local testing environment and performing tests using Mocha and Chai,
+refer to the dedicated [Testing](/build/test-and-debug) page.

content/00.build/95.resources/30.audit-bug-bounty.md

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+---
+title: Audits and Bug Bounty Program
+description:
+---
+
+ZKsync Era takes security seriously and as such, we have completed multiple audits in all critical parts of the
+protocol. On top of that, there is an ongoing massive bug bounty program.
+
+## Audits
+
+We always ensure that all code deployed to production has been thoroughly tested before release. Our auditing and
+review processes begin well before any code is deployed. We conduct internal audits, followed by independent
+external audits from reputable auditors. If applicable, we also hold a public auditing contest and top it off with another independent external audit.
+
+Here is the list of **completed audits**:
+
+- Layer 1 Smart Contracts, Internal Audit, from 2022-06-14 to 2022-08-17.
+- [Layer 1 Smart Contracts](https://blog.openzeppelin.com/zksync-layer-1-audit/), OpenZeppelin, from 2022-09-05 to 2022-09-30.
+- [Layer 1 Diff Audit (Upgrade Audit)](https://blog.openzeppelin.com/zksync-layer-1-diff-audit/), OpenZeppelin, from 2022-11-21 to 2022-11-25.
+- [Layer 1 Diff Audit (Upgrade Audit)](https://blog.openzeppelin.com/zksync-l1-diff-audit-february-2023/), OpenZeppelin, from 2023-02-06 to 2023-02-17.
+- [Layer 1 Public Contest](https://code4rena.com/reports/2022-10-zksync/), Code4rena, from 2022-10-28 to 2022-11-09.
+- [Layer 1 Smart Contracts](https://github.com/Secure3Audit/Secure3Academy/blob/main/audit_reports/zkSync/zkSync_L1_final_Secure3_Audit_Report.pdf),
+Secure3, from 2022-10-22 to 2022-11-06.
+- [WETH Bridge Audit](https://blog.openzeppelin.com/zksync-weth-bridge-audit), OpenZeppelin, from 2023-03-27 to 2023-03-31.
+- [Bridge and .transfer & .send](https://blog.openzeppelin.com/zksync-bridge-and-.transfer-.send-diff-audit), OpenZeppelin, from 2023-04-24 to 2023-05-01.
+- [GnosisSafeZk Assessment](https://blog.openzeppelin.com/zksync-gnosissafezk-assessment-1), OpenZeppelin, from 2023-05-22 to 2023-05-26.
+- [Upgrade System](https://blog.openzeppelin.com/zksync-upgrade-system-audit), OpenZeppelin, from 2023-06-26 to 2023-06-30.
+- [Layer 1 Messenger Upgrade](https://blog.openzeppelin.com/zksync-l1messenger-upgrade-audit), OpenZeppelin, from 2023-08-30 to 2023-09-14.
+- [Diff and Governance Audit](https://blog.openzeppelin.com/december-diff-and-governance-audit), OpenZeppelin, from 2023-12-04 to 2023-12-22.
+- Layer 2, Internal Audit, from 2022-08-17 to 2022-10-24.
+- [Layer 2 Bootloader](https://blog.openzeppelin.com/zksync-bootloader-audit-report/), OpenZeppelin, from 2022-11-28 to 2022-12-23.
+- [Layer 2 Fee Model and Token Bridge](https://blog.openzeppelin.com/zksync-fee-model-and-token-bridge-audit/), OpenZeppelin, from 2023-01-23 to 2023-02-17.
+- [Layer 2 System Contracts Public Contest](https://code4rena.com/contests/2023-03-zksync-era-system-contracts-contest),
+Code4rena, from 2023-03-10 to 2023-03-19.
+- [Layer 2 Block Refactor](https://blog.openzeppelin.com/zksync-l2-block-refactor-audit), OpenZeppelin, from 2023-07-25 to 2023-07-31.
+- [Keccak256 Upgrade](https://blog.openzeppelin.com/zksync-keccak256-upgrade-audit), OpenZeppelin, from 2023-10-23 to 2023-10-27.
+- [Layer 1 & 2 Diff Audit](https://blog.openzeppelin.com/november-diff-audit), OpenZeppelin, from 2023-11-27 to 2023-12-05.
+- [Short-Term Fee Model Changes](https://blog.openzeppelin.com/short-term-fee-model-changes-audit), OpenZeppelin, from 2023-12-06 to 2023-12-13.
+- ZK Proof System, Internal Audit, from 2022-10-24 to 2022-11-18.
+- [ZK Proof System](https://github.com/HalbornSecurity/PublicReports/blob/master/ZK%20Audits/MatterLabs_zkSync_Era_Circuits_Zero_Knowledge_Security_Audit_Report_Halborn_Final..pdf),
+Halborn, from 2023-01-09 to 2023-03-08.
+- [Smart Contract Security Assessment](https://github.com/HalbornSecurity/PublicReports/blob/master/Solidity%20Smart%20Contract%20Audits/MatterLabs_Verifier_Smart_Contract_Security_Assessment_Report_Halborn_Final.pdf),
+Halborn, from July 12th, 2023 - July 20th, 2023.
+- [SNARK Wrapper](https://github.com/spearbit/portfolio/blob/master/pdfs/Matter-labs-snark-wrapper-Spearbit-Security-Review.pdf), Spearbit, November 2023
+- [EIP-4844 Support](https://blog.openzeppelin.com/eip-4844-support-audit), OpenZeppelin, February 2024
+
+## Bug Bounty Program
+
+ZKsync Era has a very detailed **[Bug bounty Program on Immunefi](https://immunefi.com/bounty/zksyncera/)**. In the listing, you can
+find all the information related to assets in scope, reporting, and the payout process.
+
+### Scope
+
+The bug bounty program for ZKsync Era aims to identify and resolve
+security vulnerabilities in our system before they can be exploited by
+malicious actors. The program is open to all individuals and teams who
+are interested in participating and are willing to comply with the
+program's rules and guidelines. The scope of the program covers all aspects of our blockchain products, including smart contracts,
+protocols, portals, and any other components that are part of our ecosystem.
+
+### Requirements
+
+1. Eligibility: The bug bounty program is open to anyone who is interested in participating and who complies with the program's rules and guidelines.
+2. Responsible Disclosure: All participants must agree to follow the responsible disclosure policy and report any security vulnerabilities
+they discover to our security team in a timely and responsible manner.
+3. Rewards: The bug bounty program offers rewards to participants who discover and report security vulnerabilities. The rewards are
+determined based on the severity of the vulnerability and are paid in USDC.
+4. Reporting Guidelines: Participants must follow the reporting guidelines specified by the program.
+5. No Public Disclosure: Participants must not publicly disclose any vulnerabilities they discover until after they have been resolved by
+our security team.
+6. No Exploitation: Attacks that the reporter has already exploited themselves, leading to damage are not eligible for a reward.
+7. Legal Compliance: Participants must comply with all applicable laws and regulations, including data privacy and security laws.
+8. Program Changes: We reserve the right to modify or terminate the program at any time and without prior notice. We also reserve the
+right to disqualify any participant who violates the program's rules and guidelines.
+
+### Unscoped Bug
+
+If you think you have found a critical or major bug that is not covered by our existing bug bounty, please report it to us
+[via the Immunefi program](https://immunefi.com/bounty/zksyncera/) regardless. We will seriously consider the impact of any issues and
+may award a bounty even for out of scope assets or impacts.

content/00.build/95.resources/40.community-channels.md

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+---
+title: Community Channels
+description:
+---
+
+Engage with our vibrant community and stay updated on the latest news, insights, and discussions through our diverse channels. Here's a quick overview:
+
+## **1. Developer Discussions**
+
+A dedicated space in GitHub for developers to discuss, collaborate, and brainstorm on technical topics.
+
+[Engage in GitHub Discussions](https://github.com/zkSync-Community-Hub/zksync-developers/discussions)
+
+---
+
+## **2. Discord**
+
+Join real-time conversations, ask questions, and connect with both the team and fellow community members.
+
+[Join our Discord server](https://join.zksync.dev/)
+
+---
+
+## **3. Twitter/X**
+
+Follow us for quick updates, announcements, and trends related to our platform, updates for developers, and the broader industry.
+
+[Follow us on Twitter](https://twitter.com/zksync)
+
+[Follow our developer-focused Twitter](https://twitter.com/zkSyncDevs)
+
+---
+
+## **4. Blog**
+
+Delve deep into comprehensive articles, tutorials, and insights penned by our team.
+
+[Read our Blog](https://zksync.mirror.xyz/)
+
+---
+
+## **5. GitHub Issues**
+
+The most effective way to seek technical support is by raising an issue on GitHub. Ensure you provide a comprehensive description,
+relevant details, and steps to reproduce for prompt assistance.
+
+- **ZKsync Era Issues**: Address all queries and concerns related to ZKsync Era here. [Report ZKsync Era Issue](https://github.com/matter-labs/zksync-era/issues)
+- **era-test-node Issues**: If you're facing challenges with the era-test-node, this is the place to raise them. [Report era-test-node Issue](https://github.com/matter-labs/era-test-node/issues)
+- **SDKs Issues**: For any issues related to our Software Development Kits, kindly head over to this section. [Report SDKs Issue](https://github.com/zksync-sdk)
+
+---
+
+## **6. Telegram**
+
+Get instant updates and participate in mobile-friendly discussions on our official Telegram channel.
+
+[Join us on Telegram](https://t.me/zksync)

content/00.build/95.resources/50.contribution-track.md

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+---
+title: Contribution Track
+description:
+---
+
+Welcome to the ZKsync Contributors Track! The purpose of this track is to accelerate your journey into the thriving ZKsync development
+landscape. As a fully open-source project, we
+believe in community-driven development, and that means anyone from anywhere can contribute to shaping the future of ZKsync.
+
+This track aims to guide you in discovering various aspects of our project, inspire you to
+contribute in the ways that interest you most, and provide a pathway to connect with the ZKsync community.
+
+## Open-Source Repositories
+
+Here's a list of our key open-source repositories that you can contribute to:
+
+### ZKsync Era
+
+- [**ZKsync Era**](https://github.com/matter-labs/zksync-era): Node implementation for ZKsync Era.
+
+### Smart Contracts
+
+- [**era-contracts**](https://github.com/matter-labs/era-contracts): Submodule containing the smart contracts for ZKsync Era.
+
+### Circuit Implementation
+
+- [**era-sync_vm**](https://github.com/matter-labs/era-sync_vm): Houses the circuit implementation of zkVM specifically for ZKsync Era.
+
+### Testing and Debugging
+
+- [**era-test-node**](https://github.com/matter-labs/era-test-node): An in-memory node designed for integration testing and debugging.
+
+### Development Tools
+
+- [**zksync-cli**](https://github.com/matter-labs/zksync-cli): CLI tool that aims to simplify the development process on ZKsync.
+- [**hardhat-zksync**](https://github.com/matter-labs/hardhat-zksync): Hardhat plugins tailored for the ZKsync Network.
+
+### Documentation
+
+- [**zksync-web-era-docs**](https://github.com/matter-labs/zksync-web-era-docs): The go-to source for official ZKsync documentation.
+
+### SDK and Explorers
+
+- [**block-explorer**](https://github.com/matter-labs/block-explorer): The official block explorer for navigating the ZKsync network.
+- [**zksync-sdk**](https://github.com/zksync-sdk): Software Development Kit for ease of integration with the ZKsync network.
+
+Feel free to explore these repositories, and don't hesitate to contribute!
+
+## Why the Contributors Track?
+
+### Purpose
+
+- Facilitate easy entry for external contributors into zkSync's development ecosystem.
+- Offer a structured approach to involvement, reducing the initial overwhelm of diving into a new project.
+- Build a strong, diverse, and global community of developers who are excited about zkSync.
+
+### Who is it for?
+
+- Developers interested in blockchain and layer 2 solutions.
+- Open-source enthusiasts looking to contribute to a growing project.
+- Those interested in contract development, dApp development, ZKsync Era, and more.
+
+## The Track
+
+### Getting Started
+
+#### 1. Introduce Yourself on [ZKsync Discord](https://discord.com/invite/QKSsp7tC2x)
+
+- Join our Discord channel and say 'hi' in the `#introductions` thread. Share what interests you and what you're hoping to learn or contribute.
+
+#### 2. Follow [ZKsync Developers](https://twitter.com/zkSyncDevs) on X (formerly Twitter)
+
+- Keep up to date with the latest news, updates, and releases by following us on X.
+
+#### 3. Dive into our Official Documentation
+
+- Immerse yourself in our comprehensive official documentation to acquire essential knowledge on ZKsync. If
+you discover a typo, syntax error, or see room for improvement, submit a Pull Request to contribute to its enhancement.
+
+### Dive Into Development
+
+#### 4. Deploy Your First Contract Using [ZKsync-CLI](https://github.com/matter-labs/zksync-cli)
+
+- Familiarize yourself with the zkSync-CLI tool and deploy your first contract on the ZKsync Era testnet.
+
+#### 5. Tackle a 'Good First Issue'
+
+- Start contributing immediately by taking on a "Good First Issue" from any of our GitHub repositories. This is
+a great way to get hands-on experience and a feel for the project.
+
+### Community Engagement
+
+#### 6. Participate in [ZKsync Developer Discussions](https://github.com/zkSync-Community-Hub/zkync-developers/discussions)
+
+- Join the discourse on GitHub discussions or other community forums to provide answers, ask questions, or share insights.
+
+#### 7. Submit a [Community Tutorial](https://github.com/zkSync-Community-Hub/tutorials) or Guide
+
+- Help others by sharing your knowledge. Write a tutorial or guide, then submit it to our community contributions repository or community forums.