Align help text of virt-aa-helper with actual expectated input

When virt-aa-helper is invoked with a -u parameter followed by an actual UUID
as suggested by the help text, it throws an 'invalid UUID' error, even when the
UUID is the UUID of an existing VM.  With this adjustment of the help text,
there's a better chance of users providing the correct input.

Signed-off-by: Erik Huelsmann <ehuels@gmail.com>
Signed-off-by: Michal Privoznik <mprivozn@redhat.com>
Reviewed-by: Michal Privoznik <mprivozn@redhat.com>

src/security/virt-aa-helper.c

@@ -105,7 +105,7 @@ vah_usage(void)
             "    -R | --remove                  unload profile\n"
             "  Options:\n"
             "    -d | --dryrun                  dry run\n"
-            "    -u | --uuid <uuid>             uuid (profile name)\n"
+            "    -u | --uuid libvirt-<uuid>     AppArmor profile name\n"
             "    -h | --help                    this help\n"
             "  Extra File:\n"
             "    -f | --add-file <file>         add file to a profile generated from XML\n"