added article link (eugenp#4127)

Author: thombergs

libraries/README.md

@@ -74,6 +74,7 @@
 - [Introduction to Akka Actors in Java](http://www.baeldung.com/akka-actors-java)
 - [A Guide to Apache Commons Collections CollectionUtils](http://www.baeldung.com/apache-commons-collection-utils)
 - [A Guide to Byte Buddy](http://www.baeldung.com/byte-buddy)
+- [Java Concurrency Utility with JCTools](http://www.baeldung.com/java-concurrency-jc-tools)
 
 The libraries module contains examples related to small libraries that are relatively easy to use and does not require any separate module of its own.