documentation - git + GitHub preferred workflow

I would be great to describe in brief, and offer resources for our typical git and GitHub workflow, targeted at contributors who are new to the open source and GitHub way of project collaboration.

Two resources I really like that are applicable:

[Git Pro Book - Contributing to a Project](https://git-scm.com/book/en/v2/GitHub-Contributing-to-a-Project)

[Git for Professionals Tutorial - Tools & Concepts for Mastering Version Control with Git - YouTube](https://www.youtube.com/watch?v=Uszj_k0DGsg)