[cli-ref] Update python-mistralclient to 2.1.2
[cli-ref] Update python-mistralclient to 2.1.2

Regenerated with latest doc-tools.

Change-Id: I0c9ee37d07ce0737c62df392adcce370fc1fa7ea

openstack/openstack-manuals,openstack/openstack-manuals,openstack/openstack-manuals,openstack/openstack-manuals