A lot of comments.

Program.cs

@@ -1,15 +1,19 @@
 using System;
 
-namespace Playground
+namespace SmallInjectorDemo
 {
     internal static class Program
     {
         private static void Main()
         {
             Console.WriteLine("Small dependency injection example.");
+            Console.WriteLine();
             var injector = new SmallInjector();
+            Console.WriteLine("Register " + nameof(ServiceOne));
             injector.RegisterType<ServiceOne, IServiceOne>(true);
+            Console.WriteLine("Register " + nameof(ServiceTwo));
             injector.RegisterType<ServiceTwo, IServiceTwo>(true);
+            Console.WriteLine("Register " + nameof(UsefulClass));
             injector.RegisterType<UsefulClass>(false);
 
             Console.WriteLine();