WinterTC needs a Contributing guide

[gesa]

At the 24 July meeting of TC55, one of the required updates to committee-wide documentation addressed was a CONTRIBUTING guide. @jasnell and @andreubotella both volunteered to make an effort toward this work within the next month, so by late August. I recommend that PR be opened against the .github repo.

[thescientist13]

TC39 Contributing doc - https://github.com/tc39/ecma262/blob/main/CONTRIBUTING.md

[gesa]

You'll probably want links to these policies
https://ecma-international.org/policies/by-ipr/code-of-conduct-in-patent-matters/
https://ecma-international.org/policies/by-ipr/royalty-free-patent-policy-extension-option/