Tweak the messages so that they mention "title" rather than
"description" when operating in title mode. Also fixes one missing "%s"
before non-formatted gettext message.
Before:
$ virsh desc --title dom
No description for domain: dom
After:
$ virsh desc --title dom
No title for domain: dom
Resolves: https://bugzilla.redhat.com/show_bug.cgi?id=1140034