Create a CODE_OF_COUNDUCT.md and a CONTRIBUTING.md

[breno-helf]

I strongly believe you guys should create a CODE_OF_CONDUCT.md and a CONTRIBUTING.md. Those files would encourage new people to collaborate on the project, and will make it more aligned with open source guidelines. I can help to create those files and give examples if needed.

[valeriansaliou]

Keeping this open for later. Thank you!
Still open for PRs if you want to submit it all.

[breno-helf]

Done!