added missing markup to improve readability
added missing markup to improve readability

- according to
  http://docs.openstack.org/contributor-guide/rst-conv/inline-markups.html

Change-Id: I8ee239f93382ecaaa1c4d604d1133f4e415180b3

openstack/openstack-manuals,openstack/openstack-manuals,openstack/openstack-manuals,openstack/openstack-manuals,AlekhyaMallina-Vedams/openstack-manuals,AlekhyaMallina-Vedams/openstack-manuals,AlekhyaMallina-Vedams/openstack-manuals