Add state pattern example

src/StatePattern/TVExample/TVOnState.cs

@@ -0,0 +1,16 @@
+using System;
+using System.Collections.Generic;
+using System.Linq;
+using System.Text;
+using System.Threading.Tasks;
+
+namespace StatePattern.TVExample
+{
+    public class TVOnState : ITVState
+    {
+        public void OnPowerButtonPresed()
+        {
+            Console.WriteLine("TV turning off");
+        }
+    }
+}