Clean up index page

There were a lot of artifacts left from the HTML translation.

The toctree at the end is to suppress the errors until the remaining
docs are cleaned up.

Change-Id: I4a8f29f0be524d0a15c7c6f590ffc3ceed6ff811
Remove old HTML headers

Change-Id: I39107df88aeb89d3364ad479d8c313b7a79b9440
Merge branch 'master' of https://github.com/openstack-dev/devstack