Update README.md (eugenp#5794)

lor6 · pivovarit · commit ee6162e04b53 · 2018-11-30T08:05:42.000+01:00
diff --git a/patterns/design-patterns/README.md b/patterns/design-patterns/README.md
@@ -13,3 +13,4 @@
 - [Interpreter Design Pattern in Java](http://www.baeldung.com/java-interpreter-pattern)
 - [State Design Pattern in Java](https://www.baeldung.com/java-state-design-pattern)
 - [The Decorator Pattern in Java](https://www.baeldung.com/java-decorator-pattern)
+- [Abstract Factory Pattern in Java](https://www.baeldung.com/java-abstract-factory-pattern)
