Update view.xml note that faceplate subcommand not implemented

The faceplate subcommand gets you some usage statements but doesn't seem to actually change anything on the graphic window. If it does work it needs more documentation because I couldn't figure it out.

doc/docbook/system/mann/view.xml

@@ -111,6 +111,7 @@ subcommands:
       [<emphasis>args</emphasis>]
     </term>
     <listitem>
+      <para><emphasis remap="B" role="bold">Not Implemented.</emphasis></para>
       <para>
 	Manipulate options for the faceplate.
       </para>