Developer docs need updated

[etsauer]

Feature description

Keeping track of developer docs updates that are needed:

• https://pelorus.readthedocs.io/en/v2.0.9/Development/#updating-the-chart-versions says to use ./scripts/bump-version for chart version updates, but now we have make rc-release instead.
• We should consolidate developer setup into a single section rather than distributing bits and pieces throughout the doc.
• Some of the developer setup simply isn't covered in this doc. For example:
  • there are packages you need installed BEFORE make dev-env will work. They include gcc and python3-devel but there are probably others we are missing
• In general, very few of the make commands and when to use them are covered in this doc
• Need to better document a process of testing operator changes

How this will help you

This will lower the barrier to community contributors wanting to help make updates to Pelorus, including me.

Feature priority

⌛ It will greatly improve my experience using Pelorus

Code of Conduct

• I agree to follow Pelorus's Code of Conduct

[mateusoliveira43]

About the developer setup, I already had trouble as well #756

I think this will never be truly solved as we accept any Linux and MacOs systems

I believe the solution would be to have a container image launch the developer environment, like I do in some personal projects. Example https://github.com/mateusoliveira43/python-project-template#docker