Add a link to the AliROOT geometry description page

git-svn-id: http://root.cern.ch/svn/root/trunk@24320 27541ba8-7e3a-0410-8455-c3a389f83636

geom/geom/doc/index.txt

@@ -17,4 +17,6 @@ BEGIN_HTML
     </a></li>
     
 </ul>
+See also >a href="http://aliceinfo.cern.ch/Offline/Activities/Geometry/">the use of the geometry
+classes in AliROOT package of ALICE</a>.
 END_HTML