document required default config (#1530)

docs/src/main/paradox/release-notes/3.0.x.md

@@ -0,0 +1,25 @@
+---
+project.description: Release notes for all Alpakka Kafka 3.0.x releases.
+---
+# Alpakka Kafka 3.0.x
+
+@@@ note
+In case you are browsing a specific version's documentation: check out the [latest release notes](https://github.com/akka/alpakka-kafka/releases)
+@@@
+
+# 3.0.1
+
+## Noteworthy
+
+This version [bumped the kafka client](https://github.com/akka/alpakka-kafka/pull/1490) which changes a default config as mentiond [here](https://cwiki.apache.org/confluence/display/KAFKA/KIP-679%3A+Producer+will+enable+the+strongest+delivery+guarantee+by+default). The following error can show up in the logs:
+
+```
+org.apache.kafka.common.errors.ClusterAuthorizationException: Cluster authorization failed
+
+```
+
+In that case the following config needs to be provided in order to set the right default:
+
+```
+akka.kafka.producer.kafka-clients.enable.idempotence=false
+```

docs/src/main/paradox/release-notes/index.md

@@ -7,6 +7,7 @@
 
 @@@ index
 
+* [3.0.x](3.0.x.md)
 * [2.1.x](2.1.x.md)
 * [2.0.x](2.0.x.md)
 * [1.1.x](1.1.x.md)