Enabled the docs to generate manpages.

* changed conf.py to reference toctree.rst instead of index
* Added note to README to upgrade your sphinx to the latest version to prevent a bug with .. note:: blocks.
Updated docs README with instructions to preview the generated manfile, and where to get the one generated by sphinx.
Some more improvements on the docs readme. Removed references to website.
Merge pull request #1303 from dhrp/update-spinx-for-man

Enabled the docs to generate manpages.