document workflow to contribute exercises

[lucaferranti]

Would be good to have a CONTRIBUTING.md documenting the workflow. Writing it down would also help me clarify the steps to myself.

As a first step, let's focus on practice exercises. My understanding so far

1. Choose an exercise and update config.json, adding at least the fields name, difficulty, stub. (I am a little surprised configlet cannot do this for me).
2. run bin/configlet uuid and add the code to the uuid field in config.json
3. run bin/configlet sync --update --docs --metadata --tests --exercise $(EXERCISE-STUB) to initialize the folder
4. initialize the folder. This could be done with mason init. The add test/tests.chpl (would be nice to automate with next step)
5. Looking at problem specifications, add exercises to the tests folder.
6. write a reference solution in .meta/reference.chpl
7. from main directory, run bin/test to test the reference solution passes the tests.

[kytrinyx]

I am a little surprised configlet cannot do this for me

Me too, to be honest. It's on my list of things I'd like to make happen.

I think you have the steps right. I will show you what I'm currently doing with my generator (I'll make a little screencast sometime this week). I want to automate as many little bits as possible, but also document the process in terms that help explain why it's that way.

[kytrinyx]

I feel like maybe we can expand on this bit of documentation here: https://exercism.org/docs/building/tracks/new/add-first-exercise (or perhaps add a separate piece of documentation).

The workflow is basically the same in all language tracks.