Update all of the docstrings on public-facing APIs to numpy style

[jleibs]

This gives us proper rendering of the docstrings in the generated docs:

Maybe worth reviewing the actual generated docs locally by checking out the branch and:

just py-docs-serve

The docs in question are mostly contained within: http://127.0.0.1:8000/common/

Checklist

• I have read and agree to Contributor Guide and the Code of Conduct
• I've included a screenshot or gif (if applicable)
• I've added a line to CHANGELOG.md (if this is a big enough change to warrant it)

[emilk]

Wow, this is wonderful, and we don't have to repeat the parameter types in the docs! 🥳