Create docs

[tmcclintock]

Use the basic sphinx build and host on either RTD or github pages.

Here is the TODO checklist:

• create docs on readthedocs -- done, docs are found here
• link the docs from the readme.rst page
• link readme.rst to the index.rst page
• translate README.md into rst
• add a page describing the mathematics
• add a page on the Model object and how to set your own values to try different flights
• generate figures in a notebook and add them to the docs
• use autoapi to split up the submodules more nicely