Merge pull request eugenp#6406 from eugenp/lor6-patch-3

Update README.md

Author: lor6

patterns/design-patterns/README.md

@@ -18,3 +18,4 @@
 - [Chain of Responsibility Design Pattern in Java](http://www.baeldung.com/chain-of-responsibility-pattern)
 - [The Command Pattern in Java](http://www.baeldung.com/java-command-pattern)
 - [Java Constructors vs Static Factory Methods](https://www.baeldung.com/java-constructors-vs-static-factory-methods)
+- [The Adapter Pattern in Java](https://www.baeldung.com/java-adapter-pattern)