Improve CONTRIBUTING docs #529
Description
I'm currently going through the docs to get this project up and running so I can contribute and there's some rough edges.
For example, using a fresh git clone and running yarn test results in failed tests. And I'm not sure if that is a bug or something I'm missing from the set up docs.
Also, this project uses v1 of Yarn, but doesn't mention the version requirement. (Yarn is currently up to v3)