Update ELK images
elasticsearch:
- https://github.com/docker-library/elasticsearch/commit/a72677b: Merge pull request https://github.com/docker-library/elasticsearch/pull/193 from docker-library/diff
- https://github.com/docker-library/elasticsearch/commit/9a07fe3: Add "docker build" example command to generated Dockerfiles
logstash:
- https://github.com/docker-library/logstash/commit/e677a5a: Merge pull request https://github.com/docker-library/logstash/pull/99 from docker-library/diff
- https://github.com/docker-library/logstash/commit/0d64798: Add "docker build" example command to generated Dockerfiles
kibana:
- https://github.com/docker-library/kibana/commit/a79c4d3: Merge pull request https://github.com/docker-library/kibana/pull/93 from docker-library/diff
- https://github.com/docker-library/kibana/commit/f3512f9: Add "docker build" example command to generated Dockerfiles