Update changelog to include JENKINS-22347 for retroactive ticket.

changelog.html

@@ -88,6 +88,7 @@ Upcoming changes</a>
     (<a href="https://issues.jenkins-ci.org/browse/JENKINS-19081">issue 19081</a>)
   <li class=bug>
     Allow JDK8 to be downloaded by JDKInstaller correctly.
+    (<a href="https://issues.jenkins-ci.org/browse/JENKINS-22347">issue 22347</a>)
 </ul>
 </div><!--=END=-->
 <h3><a name=v1.556>What's new in 1.556</a> (2014/03/23)</h3>