Document attributes (#497)

* Add 'docker' action group attribute.

* Compatibility with older ansible-core releases.

* Fix typo.

* Docment standard attributes.

* Improve docs.

* Add shortcuts for common combinations.

plugins/modules/docker_stack.py

@@ -17,6 +17,13 @@ short_description: docker stack module
 description:
   - Manage docker stacks using the C(docker stack) command
     on the target node (see examples).
+extends_documentation_fragment:
+  - community.docker.attributes
+attributes:
+  check_mode:
+    support: none
+  diff_mode:
+    support: none
 options:
   name:
     description: