ES-975464 - Resolve the ReadMe file length issue in this sample repository

Author: SreemonPremkumarM

README.md

@@ -2,4 +2,37 @@
 
 ## About the example
 
-This example illustrates how to populate child nodes asynchronously in uwp treegrid
+This example illustrates how to populate child nodes asynchronously in `UWP TreeGrid`.
+
+You can populate the child nodes asynchronously using `async` and `await` at runtime when retrieving data from web services or any database. This can be performed by `PopulateChildNodes` method from `TreeGridRequestTreeItemsEventArgs.ParentNode` property.
+
+``` c#
+private async void TreeGrid_RequestTreeItems(object sender, TreeGridRequestTreeItemsEventArgs args)
+{
+    if (args.ParentItem == null)
+    {
+        args.ChildItems =  viewModel.Employees.Where(x => x.ReportsTo == -1);
+    }
+    //if ParentItem not null, then set args.ChildList to the child items for the given ParentItem.
+    else
+    {
+        EmployeeInfo ems = args.ParentItem as EmployeeInfo;
+              
+        if (ems != null)
+        {
+            await Task.Run(async () =>
+            {
+                await this.treeGrid.Dispatcher.RunAsync(CoreDispatcherPriority.High, async() =>
+                {
+                    //Get the child items with time delay
+                    var childItems = await viewModel.GetEmployees(ems.ID);
+
+                    //Populate the child nodes based on the child items
+                    args.ParentNode.PopulateChildNodes(childItems);
+                });
+                       
+            });
+        }
+    }
+}
+```