Docs: Update zookeeper image (kafbat#431)

Author: polegkashti

documentation/compose/ui-acl-with-zk.yaml

@@ -18,7 +18,7 @@ services:
       KAFKA_CLUSTERS_0_PROPERTIES_SASL_JAAS_CONFIG: 'org.apache.kafka.common.security.plain.PlainLoginModule required username="admin" password="admin-secret";'
 
   zookeeper:
-    image: wurstmeister/zookeeper:3.4.6
+    image: zookeeper:3.8
     environment:
       JVMFLAGS: "-Djava.security.auth.login.config=/etc/zookeeper/zookeeper_jaas.conf"
     volumes: