Add sphinx and Read the Docs

[zaqqwerty]

Resolves #27

Adds infrastructure for using Sphinx to generate documentation from code. Initial index.rst and reference.rst added to generate the docs. .readthedocs.yaml tweaks the default Read the Docs build to read from our Poetry compatible pyproject.toml

This build can be viewed at https://qhbm-library--240.org.readthedocs.build/en/240/. Currently LaTeX in docstrings does not render, see #242

[farice]

Sorry just saw the last line of the desc - do we want to add this extension integration now or defer to another PR?

[zaqqwerty]

Not sure what it will take to enable, so I'm thinking getting a first draft of docs up first would be good.