Added link to another example project to Readme.

Author: chclaus

README.md

@@ -4,3 +4,4 @@ Some examples for the spring universe
 - [spring-boot-mapped-supertype](https://github.com/chclaus/spring-boot-examples/tree/master/spring-boot-mapped-supertype) An example project for a very useful mapped supertype jpa entity.
 - [spring-boot-pid](https://github.com/chclaus/spring-boot-examples/tree/master/spring-boot-pid) An example project for PID generation with spring-boot.
 - [spring-boot-user-impersonation](https://github.com/chclaus/spring-boot-examples/tree/master/spring-boot-user-impersonation) An example project to show user impersonation with spring-boot.
+- [spring-boot-jpa-optimistic-locking](https://github.com/chclaus/spring-boot-examples/tree/master/spring-boot-jpa-optimistic-locking) An example project to demonstrate optimistic locking with jpa.