Switch to side-by-side view

--- a/website/doc.html
+++ b/website/doc.html
@@ -49,6 +49,8 @@
       <li><a href="perfs.html">Index size and indexing performance
 	  data.</a></li>
       <li><a href="custom.html">Result list format samples.</a></li>
+      <li><a href="idxthreads/threadingRecoll.html">Lessons learned
+          while modifying Recoll indexing to be multithreaded</a>.</li>
       <li><a href="http://bitbucket.org/medoc/recoll/wiki/FaqsAndHowTos">
           Faqs and Howtos</a> are now kept in the 
 	  <a href="http://bitbucket.org/medoc/recoll/wiki/">