Prepare repository for switch to public repository

[mayrmt]

Description and Context

Update README and add CONTRIBUTING in preparation for making this repository publicly available.

Related Issues and Pull Requests

• Part of #54

How Has This Been Tested?

Visual inspection of rendered markdown files on my machine.

Checklist

• [x] My commit messages mention the appropriate GitHub issue numbers and are longer than one line where appropriate.
• [x] I have added/updated documentation where necessary.

Additional Information

This is a first draft open for discussion. Let's not over-engineer.

Interested Parties / Possible Reviewers

@RShaw026 @NoraHagmeyer

[mayrmt]

@NoraHagmeyer I'll take care of it in a minute.

Another thought: I have including the workflow with forked repositories. I'm not sure, if this is too much for the current scale of the problem and size of the developer community. Any thoughts on this?

[NoraHagmeyer]

@NoraHagmeyer I'll take care of it in a minute.

Another thought: I have including the workflow with forked repositories. I'm not sure, if this is too much for the current scale of the problem and size of the developer community. Any thoughts on this?

@mayrmt I was wondering the same thing. I'd say it's definitely overkill for us. But, in case some external user might actually want to contribute something, it's nice to already have the instructions.