add Recommendation

src/Shared/HandyControl_Shared/Interactivity/Commands/ShutdownAppCommand.cs

@@ -0,0 +1,15 @@
+using System;
+using System.Windows;
+using System.Windows.Input;
+
+namespace HandyControl.Interactivity
+{
+    public class ShutdownAppCommand : ICommand
+    {
+        public bool CanExecute(object parameter) => true;
+
+        public void Execute(object parameter) => Application.Current.Shutdown();
+
+        public event EventHandler CanExecuteChanged;
+    }
+}