Updated openstack/openstack
Project: openstack/requirements  22a4c49fb23534865dda2610750ead26045d53b5
null
Update openstack-doc-tools to 0.6

0.6 is the latest release and a hard requirement for gating
the documentation projects.

Change-Id: I9a3e7f397c3e41f0c1e1d3f500c3eb6ff6b447df