Update README.md

Author: lairen

README.md

@@ -945,6 +945,8 @@ This configures the store to look up CA certificates from the system default cer
 
 In order to authenticate the client to the cluster, you need to pass in a certificate and key created for the client and trusted by the brokers.
 
+**NOTE**: Passing `verify_hostname: false` to disable hostname validation may be necessary if your `ssl_client_cert` is a combined certificate.
+
 ```ruby
 kafka = Kafka.new(
   ["kafka1:9092"],