changes to ch_intro.xml in high availability guide
changes to ch_intro.xml in high availability guide

remove , and since it’s listed
added “an” uptime of

Change-Id: I055baf97df6719321ecac9e33e7a43ca17a2cdfa

potsmaster/openstack-manuals,Akasurde/openstack-manuals,potsmaster/openstack-manuals,saeki-masaki/openstack-manuals,openstack/openstack-manuals,openstack/openstack-manuals,gongysh2004/openstack-manual,kairoaraujo/openstack-manuals,Akasurde/openstack-manuals,AlekhyaMallina-Vedams/openstack-manuals,AlekhyaMallina-Vedams/openstack-manuals,openstack/openstack-manuals,openstack/openstack-manuals,kairoaraujo/openstack-manuals,gongysh2004/openstack-manual,AlekhyaMallina-Vedams/openstack-manuals,saeki-masaki/openstack-manuals