We have three populated sections:
- install
- user
- reference
There are three docs removed, as they served little useful purpose and
were mostly unreferenced.
Sphinx's 'warning-is-error' option is enabled to catch the few issues
that has snuck into the docs.
Change-Id: I04e426faf337f0b03175f439c80b3369d4066733
4fc0a51a17