Add docs for contributors. about whale

[Victoriapm]

Hey, I could add a contributing.md file with the instructions on how to create a pull request and work on issues.
Let me know what you think

[Victoriapm]

I just made the pull request, probably a lot to improve with the stuff you have in mind but should be a good start with some basic guidelines. Let me know what you think, I’m open to suggestions.

I'm signing to the slack channel, will definitely have an eye on that channel.

[rsyi]

Go for it! In the end, I'll probably have to add a bit of stuff that's just in my brain right now (a QA checklist, e.g.), but I can work off your contribution.

Btw, we have a channel (#contributors) in our slack community where I'll post good first issues to familiarize yourself with the codebase + solicit help. Check it out if you're interested in helping out more in the future :)

[rsyi]

Great work, @Victoriapm! Merged, and will manually update nits :)