Comments for memento example.

memento/src/main/java/com/iluwatar/App.java

@@ -2,6 +2,15 @@ package com.iluwatar;
 
 import java.util.Stack;
 
+/**
+ * 
+ * Memento pattern is for storing and restoring object
+ * state. The object (Star) gives out a "memento" 
+ * (StarMemento) that contains the state of the object. 
+ * Later on the memento can be set back to the object 
+ * restoring the state.
+ *
+ */
 public class App 
 {
     public static void main( String[] args )