Added real world example for Singleton.

Author: iluwatar

README.md

@@ -104,6 +104,9 @@
 * managing a connection to a database
 * file manager
 
+**Real world examples:**
+* [java.lang.Runtime#getRuntime()](http://docs.oracle.com/javase/6/docs/api/java/lang/Runtime.html#getRuntime%28%29)
+
 ## <a name="adapter">Adapter</a> [&#8593;](#list-of-design-patterns)
 **Intent:** Convert the interface of a class into another interface the clients expect. Adapter lets classes work together that couldn't otherwise because of incompatible interfaces.