fix: update broken Java tutorial link

Author: Srikeerthiraja

README.md

@@ -206,7 +206,7 @@ To get started, simply fork this repo. Please refer to [CONTRIBUTING.md](CONTRIB
 - [Build an Interpreter](http://www.craftinginterpreters.com/) (Chapter 4-13 is written in Java)
 - [Build a Simple HTTP Server with Java](http://javarevisited.blogspot.com/2015/06/how-to-create-http-server-in-java-serversocket-example.html)
 - [Build an Android Flashlight App](https://www.youtube.com/watch?v=dhWL4DC7Krs) (video)
-- [Build a Spring Boot App with User Authentication](https://spring.io/guides/gs/securing-web/)
+- [Build a Spring Boot App with User Authentication](https://www.youtube.com/watch?v=KYNR5js2cXE)(video)
 
 ## JavaScript: