Add Boost.Heap notice

[SVN r76740]

index.html

@@ -55,7 +55,7 @@
 
   <h3>Changes in this release</h3>
 
-  <p>This release includes ? new libraries
+  <p>This release includes one new library, Boost.Heap,
   as well as updates to many existing libraries. See
   <a href="http://www.boost.org/users/history/version_1_49_0">Release
   History</a> for more information.</p>