docs: updating documentation to reflect Kafka compatibility

Signed-off-by: A S Adil Mohammad <Adil.Mohammad@ibm.com>

Author: A S Adil Mohammad

README.md

@@ -6,6 +6,8 @@ The connector is supplied as source code which you can easily build into a JAR f
 
 **Note**: A sink connector for IBM MQ is also available on [GitHub](https://github.com/ibm-messaging/kafka-connect-mq-sink).
 
+**Compatibility:**: This Connector supports Kafka versions upto 3.9. It is not compatible with Kafka 4.x.
+
 ## Contents
 
 - [Building the connector](#building-the-connector)