Add the start of chapter 6, still much to go.

llvm-svn: 43607
diff --git a/llvm/docs/tutorial/index.html b/llvm/docs/tutorial/index.html
index 11e93d3..56886c3 100644
--- a/llvm/docs/tutorial/index.html
+++ b/llvm/docs/tutorial/index.html
@@ -32,7 +32,7 @@
     <li><a href="LangImpl3.html">Implementing Code Generation to LLVM IR</a></li>
     <li><a href="LangImpl4.html">Adding JIT and Optimizer Support</a></li>
     <li><a href="LangImpl5.html">Extending the language: control flow</a></li>
-    <li>Extending the language: operator overloading</li>
+    <li><a href="LangImpl6.html">Extending the language: operator overloading</a></li>
     <li>Extending the language: mutable variables</li>
     <li>Thoughts and ideas for extensions</li>
   </ol></li>