Added telemetry to README

Author: hugoabernier

README.md

@@ -81,4 +81,6 @@ Sample SharePoint Framework application customiser injecting a custom CSS in the
 
 This sample illustrates the following concepts on top of the SharePoint Framework:
 
-* HTML manipulation
+* HTML manipulation
+
+<img src="https://telemetry.sharepointpnp.com/sp-dev-fx-extensions/samples/readme-template" />