[incubator/kafka] Add limitation to readme (#5104)

* Add limitation to readme

See #5089

* bump patch version for incubator/kafka

incubator/kafka/Chart.yaml

@@ -2,7 +2,7 @@ apiVersion: v1
 description: Apache Kafka is publish-subscribe messaging rethought as a distributed
   commit log.
 name: kafka
-version: 0.5.2
+version: 0.5.3
 appVersion: 4.0.1
 keywords:
 - kafka

incubator/kafka/README.md

@@ -172,5 +172,6 @@ such port at a time, setting the range at every Kafka pod is a reasonably safe c
 
 * Topic creation is not automated
 * Only supports storage options that have backends for persistent volume claims (tested mostly on AWS)
+* There must not exist a service called `kafka` in the same namespace
 
 [brokerconfigs]: https://kafka.apache.org/documentation/#brokerconfigs