Create documentation and and a readthedocs page

[ivalaginja]

For starters, set up the most rudimentary documentation page with Sphynx and make sure it works.

This will require unifying the doctoring style throughout the code.

This might be achieved in unison with #55, where we make the repo a package.

[hrwakeford]

I am going to attempt to follow the following process from @christinahedges to make a webpage with the documentation associated with ExoTiC-ISM
https://christinahedges.github.io/astronomy_workflow/notebooks/3.0-building/mkdocs.html

This will be done and tested on a fork before issuing a pull request into this repo