CONTRIBUTING: mention contributing to enterprise code, fix CoC link, etc. (!33766) · Merge requests · Administrator / sourcegraph · GitLab

Administrator requested to merge sg/contributing-cleanup into master Apr 12, 2022

Created by: slimsag

Made clear that contributing to enterprise/ code is 100% fine as long as you've signed the CLA.
Fixed URL to Code of Conduct.
Make it more clear that the big-scary-wording section about talking to us first is regarding contributing large changes (this is more contributor friendly.)

Test plan

docs change only.