Small fixes and improvements (#569)

- add .ruby-version
- update ansible min version
- update ansible galaxy tags
- fix doc and changelog

meta/main.yml

@@ -7,7 +7,7 @@ galaxy_info:
   description: Elasticsearch for Linux
   company: "Elastic.co"
   license: "license (Apache)"
-  min_ansible_version: 2.3.2
+  min_ansible_version: 2.4.2
   platforms:
   - name: EL
     versions:
@@ -19,7 +19,9 @@ galaxy_info:
   - name: Ubuntu
     versions:
     - all
-  categories:
-    - system
-
+  - galaxy_tags:
+    - elastic
+    - elasticsearch
+    - elk
+    - logging
 dependencies: []