Code of Conduct

Choo is a pretty friendly community. But as we grow, it might useful to write down some of the things we believe in — it's not so much for people already involved with Choo, but for people coming into the project.

Finding the right words can be tricky, but adopting a document that shows we believe in keeping the community friendly to everyone would probably be good.

So I was wondering if anyone has a preference for already-existing CoC's. We could write one from scratch, but given other people have spent lots of time writing similar docs already, it might make more sense to adopt one that is closest to how we as a community operate.

@choojs/trainspotters are there any CoCs you like? Thanks!

### references
- https://wealljs.org/code-of-conduct
- https://github.com/nodejs/TSC/blob/master/CODE_OF_CONDUCT.md
- https://github.com/nodeschool/berlin/blob/master/codeofconduct.md

Review the three referenced Code of Conduct documents and compare which best fits the Choo community. Done means the community has chosen or drafted a Code of Conduct and documented that decision for adoption.

Written by the indexing model from the issue text.