Add CONTRIBUTING.md

[Emilgardis]

We should add a CONTRIBUTING.md file, specifying how

• How to interact with the repository
• How to find easy issues
• Explain how cross works in a lower level than "just works"
• How to integrate new targets (explain xtask, the ci pipeline etc)
• How releases are done
• more?
• link to coc

https://docs.github.com/en/communities/setting-up-your-project-for-healthy-contributions/setting-guidelines-for-repository-contributors

[Alexhuszagh]

Maybe also add an AUTHORS.md file? Might be nice to give credit. We can also quickly grep the commit history to add one.

[Emilgardis]

Maybe also add an AUTHORS.md file? Might be nice to give credit. We can also quickly grep the commit history to add one.

I don't see the point myself, we have this https://github.com/cross-rs/cross/graphs/contributors as a substitute and it's real-time

[Alexhuszagh]

Do we still need this? We've added the contributing section to the wiki.

[Emilgardis]

I think it would be good to have, either just duplicating or making it a link to the wiki

[Alexhuszagh]

So I guess the real question is do we want it in the git history then? If so, I can duplicate it. If not, we should probably link it.