docs: add CONTRIBUTING.md file

Signed-off-by: Tarek <[email protected]>

CONTRIBUTING.md

@@ -0,0 +1,74 @@
+# CONTRIBUTING
+
+Contributions are appreciated! Follow these guidelines:
+
+- Check your code with the linter by running `make clippy`
+- Format your code using `make fmt`
+- Ensure all tests pass with `make check`
+
+## Code style
+
+The following code guidelines will help make code review smoother.
+
+### Use of `unwrap` and `expect`
+
+Use only in the following cases:
+
+1.  It's impossible for the `Result` to be an `Err`, eg. when parsing a string
+    into a type that is known to be valid.
+2.  Test code, where panicking is acceptable.
+
+In either case, add a comment explaining why it's safe to `unwrap` or `expect`
+with a comment starting with `// SAFETY: ...`.
+
+### Module imports
+
+Modules are declared at the top of the file, before the imports. Public modules
+are separated from private modules with a blank line:
+
+    mod git;
+    mod storage;
+
+    pub mod refs;
+
+    use std::time;
+    use std::process;
+
+    ...
+
+Imports are organized in groups, from least specific to more specific:
+
+    use std::collections::HashMap;   // First, `std` imports.
+    use std::process;
+    use std::time;
+
+    use git_ref_format as format;    // Then, external dependencies.
+    use once_cell::sync::Lazy;
+
+    use crate::crypto::PublicKey;    // Finally, local crate imports.
+    use crate::storage::refs::Refs;
+    use crate::storage::RemoteId;
+
+## Documentation
+
+Public types and functions should be documented with doc comments. Use `///` for
+doc comments, and `//!` for module-level documentation.
+
+## Writing commit messages
+
+Commit messages in Barq follow a structured format:
+
+```text
+<type>(<scope>): <subject>
+```
+
+- **Type:** Indicates the kind of change (e.g., feat, fix, deprecate, remove).
+- **Scope:** Optional; specifies the component affected by the change (e.g., common, plugin, docs, github)
+- **Subject:** A brief, imperative description of the change.
+  - Use present tense, imperative mood (e.g., "change", not "changed" or "changes"), and avoid ending with a dot (.)
+
+Example:
+
+```
+feat(common): add Dijkstra's routing algorithm
+```