fix(config): update example config "listeners" for brokers (#2074)

Signed-off-by: Ning Yu <[email protected]>

Author: Chillax-0v0

config/kraft/broker.properties

@@ -37,7 +37,7 @@ controller.quorum.voters=1@localhost:9093
 #     listeners = listener_name://host_name:port
 #   EXAMPLE:
 #     listeners = PLAINTEXT://your.host.name:9092
-listeners=PLAINTEXT://localhost:9092
+listeners=PLAINTEXT://:9092
 
 # Name of listener used for communication between brokers.
 inter.broker.listener.name=PLAINTEXT