Release 5.6.1

Closes #173

README.md

 # Docker ELK stack
 
-[![Join the chat at https://gitter.im/deviantony/docker-elk](https://badges.gitter.im/Join%20Chat.svg)](https://gitter.im/deviantony/docker-elk?utm_source=badge&utm_medium=badge&utm_campaign=pr-badge&utm_content=badge) [![Elastic Stack version](https://img.shields.io/badge/ELK-5.5.2-blue.svg?style=flat)](https://github.com/deviantony/docker-elk/issues/165)
+[![Join the chat at https://gitter.im/deviantony/docker-elk](https://badges.gitter.im/Join%20Chat.svg)](https://gitter.im/deviantony/docker-elk?utm_source=badge&utm_medium=badge&utm_campaign=pr-badge&utm_content=badge) [![Elastic Stack version](https://img.shields.io/badge/ELK-5.6.1-blue.svg?style=flat)](https://github.com/deviantony/docker-elk/issues/173)
 
 Run the latest version of the ELK (Elasticsearch, Logstash, Kibana) stack with Docker and Docker Compose.
 
@@ -124,7 +124,7 @@ $ curl -XPUT -D- 'http://localhost:9200/.kibana/index-pattern/logstash-*' \
 This command will mark the Logstash index pattern as the default index pattern:
 
 ```bash
-$ curl -XPUT -D- 'http://localhost:9200/.kibana/config/5.5.2' \
+$ curl -XPUT -D- 'http://localhost:9200/.kibana/config/5.6.1' \
     -H 'Content-Type: application/json' \
     -d '{"defaultIndex": "logstash-*"}'
 ```

elasticsearch/Dockerfile

 # https://github.com/elastic/elasticsearch-docker
-FROM docker.elastic.co/elasticsearch/elasticsearch:5.5.2
+FROM docker.elastic.co/elasticsearch/elasticsearch:5.6.1
 
 # Add your elasticsearch plugins setup here
 # Example: RUN elasticsearch-plugin install analysis-icu

elasticsearch/config/elasticsearch.yml

@@ -22,5 +22,4 @@ discovery.type: single-node
 xpack.security.enabled: false
 xpack.monitoring.enabled: false
 xpack.ml.enabled: false
-xpack.graph.enabled: false
 xpack.watcher.enabled: false

kibana/Dockerfile

 # https://github.com/elastic/kibana-docker
-FROM docker.elastic.co/kibana/kibana:5.5.2
+FROM docker.elastic.co/kibana/kibana:5.6.1
 
 # Add your kibana plugins setup here
 # Example: RUN kibana-plugin install <name|url>

kibana/config/kibana.yml

@@ -15,3 +15,4 @@ xpack.monitoring.enabled: false
 xpack.ml.enabled: false
 xpack.graph.enabled: false
 xpack.reporting.enabled: false
+xpack.grokdebugger.enabled: false

logstash/Dockerfile

 # https://github.com/elastic/logstash-docker
-FROM docker.elastic.co/logstash/logstash:5.5.2
+FROM docker.elastic.co/logstash/logstash:5.6.1
 
 # Add your logstash plugins setup here
 # Example: RUN logstash-plugin install logstash-filter-json