Commented flyweight example.

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

@@ -1,5 +1,12 @@
 package com.iluwatar;
 
+/**
+ * 
+ * Flyweight (PotionFactory) is useful when there is plethora of
+ * objects (Potion). It provides means to decrease resource usage
+ * by sharing object instances.
+ *
+ */
 public class App 
 {
     public static void main( String[] args )