Comment 2 for bug 1758104

Reviewed: https://review.openstack.org/555373
Committed: https://git.openstack.org/cgit/openstack/python-cinderclient/commit/?id=d6c6011fc83ab9a3bbd65e8dd4557ebf25b363ae
Submitter: Zuul
Branch: master

commit d6c6011fc83ab9a3bbd65e8dd4557ebf25b363ae
Author: j-griffith <email address hidden>
Date: Thu Mar 22 10:50:51 2018 -0600

    Update python usage docs

    The keystoneauth1 get_plugin_loader method requires that a
    OS_USER_DOMAIN be specified. Our docs don't include that
    detail.

    This change adds the extra needed field. There's also some
    problems currently with loading the client directly as it's
    currently documented, which appears to be a bug in the client
    code itself.

    Change-Id: Idacbb47f9aae1e461379eec4a5e224b0157a8dc4
    Partial-Bug: #1758104