Updated openstack/openstack
Project: openstack/python-cinderclient  6550b0ab5c4602dde1a09f528de35c304253bbc7

Remove "OPTIONAL:" from optional argument help text

All arguments starting with '--' are optional and listed
under the 'Optional arguments:' header by argparse.  Remove
the extra note shown for each argument.

Change-Id: Ic361a3bdbd1f1669458e16b99995f0f108400699