Prelim docs

[rebeccabilbro]

This PR fixes sc-20959 which requested some preliminary PyEnsign docs that we could host on read the docs and link to from the ensign docs. This should also make it easier for PyEnsign contributors to contribute to the PyEnsign docs!

I have made the following changes:

1. Set up a new sphinx project inside the docs/ folder
2. Added some preliminary content, but mainly just to show how we can integrate our own text with the PyEnsign code using the autodoc feature in Sphinx.

Questions for the @pdeziel

• Anything else you think we should include?

CHECKLIST

• Is the commit message formatted correctly?

• Do all of your functions and methods have docstrings?
• Have you added/updated unit tests where appropriate?
• Have you run the unit tests using pytest?
• Is your code style correct (are you using PEP8, pyflakes)?

[shortcut-integration]

This pull request has been linked to Shortcut Story #20959: Create prelim RTD docs for PyEnsign.

[pdeziel]

Looks good, can't wait to see how this looks!