Fix link to 21773

changelog.html

@@ -65,7 +65,7 @@ Upcoming changes</a>
 <ul class=image>
   <li class=bug>
     Fixed Up link in matrix projects
-    (<a href="https://issues.jenkins-ci.org/browse/JENKINS-21958">issue 21773</a>)
+    (<a href="https://issues.jenkins-ci.org/browse/JENKINS-21773">issue 21773</a>)
 </ul>
 </div><!--=END=-->
 <h3><a name=v1.554>What's new in 1.554</a> (2014/03/09)</h3>