fix link to java regex tutorial

git-svn-id: http://svn.igniterealtime.org/svn/repos/openfire/trunk@12589 b35dd754-fafc-0310-a699-88a17e54d16e

src/plugins/contentFilter/readme.html

@@ -84,7 +84,7 @@ If you choose to filter your users presence status and there is a content match
 </ul>
 </p>
 <p>
-Want to know more about regular expressions in Java? This official <a href="http://java.sun.com/docs/books/tutorial/extra/regex/">tutorial</a>
+Want to know more about regular expressions in Java? This official <a href="http://java.sun.com/developer/technicalArticles/releases/1.4regex/">tutorial</a>
 is useful.
 </p>