Contributing Documentation - Testing

[nina-sanchez]

Hello! I am new to twenty and have been going through the documentation to better understand how to work on issues, contributing guidelines etc. As I was going through it I read that it should be tested locally - but also saw that at times testing suites were provided with the PR. Because of that I added to my local CONTRIBUTING.md file a testing suite section to provide some clarity - and will attach the image below. Let me know some thoughts on this addition!