Update a comment in qa-sample.json

Fix the sentence to say what it means.

Signed-off-by: Guido Trotter <ultrotter@google.com>
Reviewed-by: Michael Hanselmann <hansmi@google.com>

qa/qa-sample.json

@@ -87,9 +87,9 @@
     "# Disabled by default because it takes rather long": null,
     "instance-replace-disks": false,
 
-    "# Make sure not to include the disk(s) required for Dom0 to be": null,
-    "# included in the volume group used for instances. Otherwise": null,
-    "# whole system may stop working until restarted.": null,
+    "# Make sure not to include the disk(s) required for Dom0 to be up": null,
+    "# in the volume group used for instances. Otherwise the whole": null,
+    "# system may stop working until restarted.": null,
     "instance-disk-failure": false
   },