Updated RadListBox example's readme

ListBox/SelectedItems/Readme.txt

@@ -1,2 +1,9 @@
+#Create attached property for SelectedItems#
+IMPORTANT:
+
+With the release of Telerik UI for WPF Q1 2015 there is a new functionality for achieving MVVM scenarios where the SelectedItems of the RadListBox should be bound to a collection from the view model. More details can be found in our online documentation: 
+- For WPF here: http://docs.telerik.com/devtools/wpf/controls/radlistbox/features/selecteditemssource
+- For Silverlight here: http://docs.telerik.com/devtools/silverlight/controls/radlistbox/features/selecteditemssource
+
 This example demonstrates how to create an attached property that could be used in order to bind a collection of objects to the control 
 and use it as a collection of selected items for Silverlight and WPF.