Add contribution guidelines about jest-webextension-mock HOT 1 OPEN

FYI the repo has moved over to https://github.com/RickyMarou/jest-webextension-mock/

That's a great suggestion that is on my radar, i already made the move to use changesets so it'll be easier to write changelogs for this project.

Essentially what I want to do is:

• Clarify the goal of the library (i.e. it's mocking webext apis, not strictly sticking to the specs but more to the real world of what is available in browsers, especially chrome)
• Write contribution guidelines
• Better automation in general
  • Redo the npm publish automation (I disabled the current one it was using a github action that has not been used for many years and I want to increase security a bit)
  • Automatically git tag and create github releases
  • Maybe enforce conventional commis on some level, albeit i'm not particularly fan of those

from jest-webextension-mock.