Update free-programming-books.md (#4170)

free-programming-books.md

@@ -1559,6 +1559,7 @@ Kerridge (PDF) (email address *requested*, not required)
 * [Java, Java, Java Object-Oriented Problem Solving](https://archive.org/details/JavaJavaJavaObject-orientedProblemSolving/page/n0) - R. Morelli and R.Walde
 * [Java Language and Virtual Machine Specifications](https://docs.oracle.com/javase/specs/) - James Gosling, et al
 * [Java Notes for Professionals](http://books.goalkicker.com/JavaBook/) - Compiled from StackOverflow documentation (3.x)
+* [Java Programming](https://en.wikibooks.org/wiki/Java_Programming/) - Wikibooks
 * [Java Programming for Kids](https://yfain.github.io/Java4Kids/) - Yakov Fain
 * [Java Projects, Second Edition](https://www.packtpub.com/free-ebooks/java-projects-second-edition) - Peter Verhas (Packt account *required*)
 * [Microservices Best Practices for Java](https://www.redbooks.ibm.com/redbooks/pdfs/sg248357.pdf) (PDF)