Following stricter docstring formatting

[sobolevnrm]

I've been loosely following Google-style docstrings in the code; it would be better to follow the official Python guidance.

[sobolevnrm]

Or just do a better job following this: https://sphinxcontrib-napoleon.readthedocs.io/en/latest/index.html

[orbeckst]

I started a Style Guide on the wiki – @sobolevnrm @speleo3 please edit as necessary, these are just stubs. But I think it's helpful to start aggregating best practices and information as this makes it a lot easier when on-boarding other contributors (and our future selves, of course).

[sobolevnrm]

Fantastic -- thank you, @orbeckst !