core/plugins/org.eclipse.dltk.core.doc.isv/plugin.xml

<?xml version="1.0" encoding="UTF-8"?>
<?eclipse version="3.2"?>
<plugin>

   <extension point="org.eclipse.help.toc"> 
       <toc file="toc.xml" primary="true" />
       <index
             path="index">
       </index>
   </extension>

</plugin>