Added real world example for Observer.

iluwatar · iluwatar · commit 420491429f8c · 2015-02-25T21:07:40.000+02:00
diff --git a/README.md b/README.md
@@ -310,6 +310,8 @@
 
 * changing in one object leads to a change in other objects
 
+**Real world examples:**
+* [java.util.Observer](http://docs.oracle.com/javase/6/docs/api/java/util/Observer.html)
 
 ## <a name="state">State</a> [&#8593;](#list-of-design-patterns)
 **Intent:** Allow an object to alter its behavior when its internal state changes. The object will appear to change its class.
