Clarify for review command when --verified can be used

Change-Id: I4051e9c3e7238b63224582f15a8666c7b599e0b3
Signed-off-by: Edwin Kempin <edwin.kempin@sap.com>

Documentation/cmd-review.txt

diff --git a/Documentation/cmd-review.txt b/Documentation/cmd-review.txt
index 97eb746..ed31e3db3 100644
--- a/Documentation/cmd-review.txt
+++ b/Documentation/cmd-review.txt
@@ -82,8 +82,9 @@
         Set the label to the value 'N'.  The exact option names
         supported and the range of values permitted differs per site,
         check the output of --help, or contact your site administrator
-        for further details.  These options are only available for these
-        built-in labels; for other labels, see --label.
+        for further details.  These options are only available for the
+        labels that are defined in the 'All-Projects' root project and
+        that are valid for all projects; for other labels, see --label.
 
 --label::
         Set a label by name to the value 'N'.