Remove "OPTIONAL:" from optional argument help text (v2)
Remove "OPTIONAL:" from optional argument help text (v2)

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

This mirrors the previous change which cleaned this up for v1:
811af8f Remove "OPTIONAL:" from optional argument help text

Change-Id: Ie8e9544c1544ff5403f1c29e83d528d896957899

scottdangelo/cinderclient-api-microversions,eayunstack/python-cinderclient,eayunstack/python-cinderclient,scottdangelo/cinderclient-api-microversions