Fix typo in devstack plugin comments
Fix typo in devstack plugin comments

Change-Id: Iffb9e244c241e37424da715a3e968b3dceb3d205

sapcc/monasca-api,openstack/monasca-api,stackforge/monasca-api,sapcc/monasca-api,openstack/monasca-api,stackforge/monasca-api,openstack/monasca-api,sapcc/monasca-api,stackforge/monasca-api,stackforge/monasca-api