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_security_group.py

@@ -31,8 +31,6 @@ options:
    description:
      description:
         - Long description of the purpose of the security group
-     required: false
-     default: None
    state:
      description:
        - Should the resource be present or absent.
@@ -41,7 +39,6 @@ options:
    availability_zone:
      description:
        - Ignored. Present for backwards compatibility
-     required: false
 '''
 
 EXAMPLES = '''