No TOC in sidebar with readthedocs theme

The rdt sphinx theme doesn't render index file sections into the TOC, making the page hard to browse. This commit moves all sections into their own files, so rtd looks like [this](http://djanotables2-doctest.readthedocs.org/en/latest/index.html).

This is a one-to-one translation of the existing sections, and IMO looks great on RTD. However it results in lots of small files and seems to break TOC rendering with the default sphinx theme... So there might be better ways to fix this, but I am not sure how atm. Just changing the theme on rtd to sphinx's default would be one way without needing to touch the code, but I quite like the rtd theme. What do you think?