Update README.md

Author: nemigasrv

j2se/java-jms-demo/README.md

@@ -3,6 +3,7 @@
 This tutorial contains Java/J2SE sample application for JMS built using Kaazing Java WebSocket JMS API
 
 ## Building and running the application
+__Note__: Make sure that you have Gradle 2.10 or higher installed.
 - Build the application using gradle
 ```bash
 cd <application root directory>