add changelog entry for maven wagon upgrade to 2.1

changelog.html

@@ -74,6 +74,8 @@ Upcoming changes</a>
   <li class=rfe>
     add new action type to enable plugins to intercept the maven 'goals and options' 
     (<a href="https://github.com/jenkinsci/jenkins/pull/316">pull #316</a>)
+  <li class=rfe>
+    Upgrade to Maven Wagon 2.1 which supports preemptive authz for dav deployment.
 </ul>
 </div><!--=TRUNK-END=-->