On `charmcraft publish-lib` we could validate library docstrings: - that they comply with the [google convention](https://google.github.io/styleguide/pyguide.html) and other "style" verifications - that all attributes/arguments are properly explained in the respective docstrings, and other warnings that may arise when rendering docstrings to HTML (server is using [this extractor](https://pypi.org/project/docstring-extractor/))