Moved the apidocs from openstack/database-api

By hosting the docs here we'll be able to better maintain that
developers are being mindful of changes or even occassionally writing
documentation for new API features. This should also allow us to
autogenerate the snippets.

Change-Id: I0111bcd38341b1736a47b0a3d3e6ff96d2ca1c58
Merge "Moved the apidocs from openstack/database-api"