Add group filtering to :command and :autocommand listings.

common/locale/en-US/autocommands.xml

@@ -42,7 +42,8 @@
         <p>
             If the <em>-group</em>=<a>group</a> flag is given, add this autocmd
             to the named <t>group</t>. Any filters for <a>group</a> apply in
-            addition to <oa>filter</oa>.
+            addition to <oa>filter</oa>. When listing commands this limits the
+            output to the specified group.
         </p>
 
         <p>Available <oa>events</oa>:</p>

common/locale/en-US/map.xml

@@ -146,7 +146,7 @@
     <dt>-count</dt> <dd>Accept a count before the requisite key press. Sets the <tt>count</tt> parameter to the result. (short name <em>-c</em>)</dd>
     <dt>-description</dt> <dd>A description of this mapping (short name <em>-d</em>)</dd>
     <dt>-ex</dt> <dd>Execute <a>rhs</a> as an Ex command rather than keys (short name <em>-e</em>)</dd>
-    <dt>-group=<a>group</a></dt> <dd>Add this command to the given <t>group</t> (short name <em>-g</em>)</dd>
+    <dt>-group=<a>group</a></dt> <dd>Add this command to the given <t>group</t> (short name <em>-g</em>). When listing commands this limits the output to the specified group.</dd>
     <dt>-javascript</dt> <dd>Execute <a>rhs</a> as JavaScript rather than keys (short names <em>-js</em>, <em>-j</em>)</dd>
     <dt>-literal=<a>n</a></dt> <dd>Parse the <a>n</a>th argument without specially processing any quote or meta characters. (short name <em>-l</em>)</dd>
     <dt>-modes=<a>modes</a></dt> <dd>Create this mapping in the given modes (short names <em>-mode</em>, <em>-m</em>)</dd>
@@ -591,7 +591,8 @@
 
         <p>
             The <em>-group</em> flag (short name: <em>-g</em>) can be used to
-            assign this command to a specific <t>group</t>.
+            assign this command to a specific <t>group</t>.  When listing
+            commands this limits the output to the specified group.
         </p>
 
         <h3 tag="E175 E176 :command-nargs">Argument handling</h3>