Add Code of Conduct

[jsolbrig]

Requested Update

Description

Add a code of conduct to the documentation.

Background and Motivation

As GeoIPS grows it is important for us to adopt a code of conduct before we have problems, not after.

Checklist for Completion

• [ ] Identify a code of conduct.
• [ ] Add the code of conduct.
• [ ] Ensure the documentation builds with the new code of conduct.