Intern Guide: How to contribute to JupyterHub and the Contribution phase

[sgibson91]

This PR adds a section to the Intern Guide that orients them to the JupyterHub Project, how they can begin contributing, and where to find the contribution issues.

ref: #45

Links to rendered docs:

• Application Criteria
• Contributing to JupyterHub

[sgibson91]

@alwasega @Sheila-nk @bl-aire Here is another documentation PR where your input would be really valuable :)

[bl-aire]

@alwasega @Sheila-nk @bl-aire Here is another documentation PR where your input would be really valuable :)

The guide is packed with resources and information that applicants will find very helpful.

Building open source software is a collaborative venture, and effective communication is key to making it successful.

This was my favourite part. The contribution phase can be really competitive. Due to this, one can get tempted to hoard information going totally against what open-source contribution entails. It is great that the intern guide contains this so rather than see the Contribution phase as a competition, one is open to networking, learning from and even teaching others.

[GeorgianaElena]

❤️ LGTM