Docstring format convention

[fabianegli]

Description of feature

I think it would be great to decide on a docstring format for this project to have a chance to use them consistently throughout the codebase for documentation and the generation of user friendly API docs.

The formats I like most are the one from Google and numpy with a slight preference for the latter.

[ewels]

Yeah this one has been on my radar for a while too. I would also like to convert the Sphinx site that we have for linting docs to use MkDocs and MkDocStrings, so was hoping to do this as part of the same effort.

I think MkDocStrings only supports Google style (may be worth checking), so my vote would be for that.

[ewels]

This looks useful: https://github.com/pycqa/pydocstyle