update changelog: PR 1682 -> issue 28233, fix markup issue

changelog.html

@@ -64,10 +64,10 @@ Upcoming changes</a>
 <ul class=image>
   <li class=bug>
     Update bundled LDAP plugin in order to restore missing help files
-    (<a href="https://github.com/jenkinsci/jenkins/pull/1682">PR 1682</a>)
+    (<a href="https://issues.jenkins-ci.org/browse/JENKINS-28233">issue 28233</a>)
   <li class=bug>
     hudson.model.Run.getLog() throws IndexOutOfBoundsException when called with maxLines=0
-    (<a href="https://issues.jenkins-ci.org/browse/JENKINS-27441">issue 27441</code>)
+    (<a href="https://issues.jenkins-ci.org/browse/JENKINS-27441">issue 27441</a>)
 </ul>
 <h3><a name=v1.612>What's new in 1.612</a> (2015/05/03)</h3>
 <ul class=image>