Update README.md

Author: pollyndos

README.md

@@ -4,6 +4,8 @@ The example shows how to get underlying data for the specified dashboard item.
 
 ![](dashboard-and-grid.png)
 
+The example uses the [`ViewerApiExtension.requestUnderlyingData`](https://docs.devexpress.com/Dashboard/js-DevExpress.Dashboard.ViewerApiExtension?p=netframework#js_devexpress_dashboard_viewerapiextension_requestunderlyingdata) method and passes the component name of the dashboard item and specific parameters to request data.
+
 ## Files to Look At
 
 - [UnderlyingData.js](./CS/MvcDashboard_UnderlyingData/Scripts/UnderlyingData.js)