Add documentation for llvm-diff.



git-svn-id: https://llvm.org/svn/llvm-project/llvm/trunk@113303 91177308-0d34-0410-b5e6-96231b3b80d8
diff --git a/docs/CommandGuide/index.html b/docs/CommandGuide/index.html
index 72cd2cf..8854fbb 100644
--- a/docs/CommandGuide/index.html
+++ b/docs/CommandGuide/index.html
@@ -72,6 +72,9 @@
 <li><a href="/cmds/llvmc.html"><b>llvmc</b></a> -
     a generic customizable compiler driver</li>
 
+<li><a href="/cmds/llvm-diff.html"><b>llvm-diff</b></a> -
+    structurally compare two modules</li>
+
 </ul>
 
 </div>