Clean up module documentation (#36909)

* Clean up module documentation

This PR includes:
- Removal of `default: None` (and variations)
- Removal of `required: false`
- Fixing booleans and `type: bool` where required

* Fix remaining (new) validation issues

lib/ansible/modules/cloud/openstack/os_server_action.py

@@ -32,13 +32,12 @@ options:
    wait:
      description:
         - If the module should wait for the instance action to be performed.
-     required: false
+     type: bool
      default: 'yes'
    timeout:
      description:
         - The amount of time the module should wait for the instance to perform
           the requested action.
-     required: false
      default: 180
    action:
      description:
@@ -50,12 +49,10 @@ options:
    image:
      description:
        - Image the server should be rebuilt with
-     default: null
      version_added: "2.3"
    availability_zone:
      description:
        - Ignored. Present for backwards compatibility
-     required: false
 requirements:
     - "python >= 2.6"
     - "shade"