virsh: fix few typos on desc command

virsh help fix:
 - <--title> can also /get/ the title

virsh man page:
 - missing <domain-id>
 - <new_desc> should be <new-desc>

tools/virsh.c

@@ -1227,7 +1227,7 @@ static const vshCmdOptDef opts_desc[] = {
     {"live", VSH_OT_BOOL, 0, N_("modify/get running state")},
     {"config", VSH_OT_BOOL, 0, N_("modify/get persistent configuration")},
     {"current", VSH_OT_BOOL, 0, N_("modify/get current state configuration")},
-    {"title", VSH_OT_BOOL, 0, N_("modify the title instead of description")},
+    {"title", VSH_OT_BOOL, 0, N_("modify/get the title instead of description")},
     {"edit", VSH_OT_BOOL, 0, N_("open an editor to modify the description")},
     {"new-desc", VSH_OT_ARGV, 0, N_("message")},
     {NULL, 0, 0, NULL}

tools/virsh.pod

@@ -497,8 +497,9 @@ Define a domain from an XML <file>. The domain definition is registered
 but not started.  If domain is already running, the changes will take
 effect on the next boot.
 
-=item B<desc> [[I<--live>] [I<--config>] | [I<--current>]] [I<--title>]
-              [I<--edit>] [I<--new-desc> New description or title message]
+=item B<desc> I<domain-id> [[I<--live>] [I<--config>] |
+              [I<--current>]] [I<--title>] [I<--edit>] [I<--new-desc>
+              New description or title message]
 
 Show or modify description and title of a domain. These values are user
 fields that allow to store arbitrary textual data to allow easy
@@ -516,7 +517,7 @@ description or title should be opened and the contents saved back afterwards.
 
 Flag I<--title> selects operation on the title field instead of description.
 
-If neither of I<--edit> and I<--new_desc> are specified the note or description
+If neither of I<--edit> and I<--new-desc> are specified the note or description
 is displayed instead of being modified.
 
 =item B<destroy> I<domain-id> [I<--graceful>]