Update README.md: Add screenshot and update link to live demo

Author: giovanni-a

README.md

@@ -4,7 +4,7 @@ This repository contains the source code of the sample OpenSilver application th
 
 Note: the source code of Telerik UI is not provided here.
 
-You can see an online demo of this application at: http://opensilvertelerik.azurewebsites.net
+You can see an online demo of this application at: https://opensilver.net/gallery/
 
 To compile and run this sample application from this repository, you need:
 - Visual Studio 2022
@@ -15,3 +15,7 @@ You will also need:
 2. A license for the OpenSilver Compatibility Pack for Telerik UI. To buy it, please contact us at: https://opensilver.net/contact.aspx
 
 For more information, please contact us at: https://opensilver.net/contact.aspx
+
+Screenshot:
+
+![image](https://github.com/OpenSilver/OpenSilver.Samples.TelerikUI/assets/8248552/15a098c5-5766-486f-b522-0f91efd16920)