Add CONTRIBUTING.md.

[VJalili]

This PR adds the contributing.md that includes guidelines on code contribution and bug reporting.

[mwalker174]

Thanks for taking the initiative on this! Can you put the text into a Google doc? I think we will need to draft this a bit before merging.

[VJalili]

That is a good point; I will share the Google doc with you.

[mwalker174]

Thank you for writing this up. A lot of good info here, particularly for newer devs who may not be familiar with github workflows.

I think we still need a few more sections for some steps that we typically go through before putting up a PR.

For WDL updates,

1. Updating corresponding template and inputs jsons in /inputs
2. Rebuilding inputs with build_default_inputs.sh as described in the README
3. Validating with womtool and miniwdl using the scripts in /scripts/test
4. Performing a test run on Terra (standalone Cromwell servers are to be deprecated soon)
5. Information on updating the Terra workspace configurations would also be useful

For backend code (i.e. mostly stuff in /src and /dockerfiles:

1. Rebuilding and pushing the docker with build_docker.py
2. Running a test in Terra
3. Updating dockers.json and dockers_azure.json if necessary, i.e. when it's not an auto-built docker

This is getting to be a long list, so maybe these belong on the website as a part of development documentation, but if we are going to expect users to actually commit changes and post PRs, they will need the rest of this information to get to that point.

[mwalker174]

Does VS have a WDL plugin? If not we may want to just suggest pycharm.

[VJalili]

Thanks, @mwalker174! Those points are all great; we can extend this contributing file or add a section to the docs to explain these steps in detail.