elk change to docker official repository

elasticsearch/Dockerfile

@@ -1,4 +1,4 @@
 ARG ELK_VERSION
-FROM docker.elastic.co/elasticsearch/elasticsearch:${ELK_VERSION}
+FROM elasticsearch:${ELK_VERSION}
 
 EXPOSE 9200 9300

kibana/Dockerfile

@@ -1,4 +1,4 @@
 ARG ELK_VERSION
-FROM docker.elastic.co/kibana/kibana:${ELK_VERSION}
+FROM kibana:${ELK_VERSION}
 
 EXPOSE 5601

logstash/Dockerfile

@@ -1,5 +1,5 @@
 ARG ELK_VERSION
-FROM docker.elastic.co/logstash/logstash:${ELK_VERSION}
+FROM logstash:${ELK_VERSION}
 
 USER root
 RUN rm -f /usr/share/logstash/pipeline/logstash.conf