[JENKINS-9791] add changelog entry

changelog.html

@@ -62,6 +62,9 @@ Upcoming changes</a>
   <li class=rfe>
     CLI command page now lists all the available commands
     (<a href="http://issues.jenkins-ci.org/browse/JENKINS-9789">issue 9789</a>)
+  <li class=rfe>
+    Improve the post deployment job to make a clear error if you disabled artifacts archives
+    (<a href="http://issues.jenkins-ci.org/browse/JENKINS-9791">issue 9791</a>)
 </ul>
 </div><!--=TRUNK-END=-->