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_user_role.py

@@ -30,27 +30,19 @@ options:
      description:
         - Name or ID for the user. If I(user) is not specified, then
           I(group) is required. Both may not be specified.
-     required: false
-     default: null
    group:
      description:
         - Name or ID for the group. Valid only with keystone version 3.
           If I(group) is not specified, then I(user) is required. Both
           may not be specified.
-     required: false
-     default: null
    project:
      description:
         - Name or ID of the project to scope the role association to.
           If you are using keystone version 2, then this value is required.
-     required: false
-     default: null
    domain:
      description:
         - ID of the domain to scope the role association to. Valid only with
           keystone version 3, and required if I(project) is not specified.
-     required: false
-     default: null
    state:
      description:
        - Should the roles be present or absent on the user.
@@ -59,7 +51,6 @@ options:
    availability_zone:
      description:
        - Ignored. Present for backwards compatibility
-     required: false
 requirements:
     - "python >= 2.6"
     - "shade"