added composite sample

composite/src/main/java/com/iluwatar/Letter.java

@@ -0,0 +1,21 @@
+package com.iluwatar;
+
+public class Letter extends LetterComposite {
+
+	private char c;
+
+	public Letter(char c) {
+		this.c = c;
+	}
+
+	@Override
+	protected void printThisBefore() {
+		System.out.print(c);
+	}
+
+	@Override
+	protected void printThisAfter() {
+		// nop
+	}
+
+}