Fixed package name of PropertyEventListener class.

git-svn-id: http://svn.igniterealtime.org/svn/repos/wildfire/branches@5979 b35dd754-fafc-0310-a699-88a17e54d16e

3_1_branch/documentation/docs/plugin-dev-guide.html

@@ -423,7 +423,7 @@ points that are the most common:
     <li>You can store persistent plugin settings as Wildfire properties using the
     JiveGlobals.getProperty(String) and JiveGlobals.setProperty(String, String) methods. Make
     your plugin a property listener to listen for changes to its properties by implementing the
-    <tt>org.jivesoftware.wildfire.event.PropertyEventListener</tt> method.
+    <tt>org.jivesoftware.util.PropertyEventListener</tt> method.
     You can register your plugin as a listener using the PropertyEventDispatcher.addListener(PropertyEventListener)
     method. Be sure to unregister your plugin as a listener in your plugin's destroyPlugin() method.