fix duallistbox link in pages/forms/advanced

pages/forms/advanced.html

@@ -972,7 +972,7 @@
           </div>
           <!-- /.card-body -->
           <div class="card-footer">
-            Visit <a href="https://select2.github.io/">Select2 documentation</a> for more examples and information about
+            Visit <a href="https://github.com/istvan-ujjmeszaros/bootstrap-duallistbox#readme">Bootstrap Duallistbox</a> for more examples and information about
             the plugin.
           </div>
         </div>