Fix link to global module index.

Doc/tools/sphinxext/indexcontent.html

@@ -32,7 +32,7 @@
   <p><strong>Indices and tables:</strong></p>
   <table class="contentstable" align="center"><tr>
     <td width="50%">
-      <p class="biglink"><a class="biglink" href="{{ pathto("modindex") }}">Global Module Index</a><br/>
+      <p class="biglink"><a class="biglink" href="{{ pathto("py-modindex") }}">Global Module Index</a><br/>
          <span class="linkdescr">quick access to all modules</span></p>
       <p class="biglink"><a class="biglink" href="{{ pathto("genindex") }}">General Index</a><br/>
          <span class="linkdescr">all functions, classes, terms</span></p>