README.md in logstash-input-kafka-5.1.7 vs README.md in logstash-input-kafka-5.1.8

@@ -4,9 +4,18 @@
 
 This is a plugin for [Logstash](https://github.com/elastic/logstash).
 
 It is fully free and fully open source. The license is Apache 2.0, meaning you are pretty much free to use it however you want in whatever way.
 
+## Logging
+
+Kafka logs do not respect the Log4J2 root logger level and defaults to INFO, for other levels, you must explicitly set the log level in your Logstash deployment's `log4j2.properties` file, e.g.:
+```
+logger.kafka.name=org.apache.kafka
+logger.kafka.appenderRef.console.ref=console
+logger.kafka.level=debug
+```
+
 ## Documentation
 
 https://www.elastic.co/guide/en/logstash/current/plugins-inputs-kafka.html
 
 Logstash provides infrastructure to automatically generate documentation for this plugin. We use the asciidoc format to write documentation so any comments in the source code will be first converted into asciidoc and then into html. All plugin documentation are placed under one [central location](http://www.elastic.co/guide/en/logstash/current/).