Updated openstack/openstack
Project: openstack/keystone  1b2c47cb46ea4cea996f276d530255e77f283928

Update docs to reflect new db_sync behaviour

In the extension specific configuration docs, we ask that the user
always migrate the extension, however now that we migrate certain
extensions by default, we can mark those steps as optional.

Change-Id: I3d2419786d1f6c25b69c29629a47892fa682129d