Fixes three small grammar errors in the ubuntu image guide
Fixes three small grammar errors in the ubuntu image guide

1) Missing a space after some quotes on line 81
2) The word "paused" was duplicated on line 138
3) The word "instance" was used instead of "installation" on line 184

Change-Id: I583a6fc721b12018ae84da70d9f0d9ccab09f198
Closes-Bug: #1420477

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