Investigate generation of documentation

[danieldk]

Investigate current possibilities for documentation generation in pyo3 and pyo3-pack. Ideally, we'd generate something similar to readthedocs. This is the last item from #5.

[RealNicolasBourbaki]

I have tried a few things, and it seems Sphinx is a very nice option.
we can use automodule and autoclass to build doc base on docstrings in rust.
here is an example project: https://fastobo.readthedocs.io/en/latest/
and the code is here: https://github.com/fastobo/fastobo-py/tree/master/docs

another option is generate json file based on rust docstrings, and use Sphinx to generate documentation. But it seems a bit unnecessary since automodule and autoclass can already handle docstrings very well.

The style is also Read the Docs.

[danieldk]

Closing this issue, as it applied to the Rust version of the module.