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/system/osx_defaults.py

@@ -27,14 +27,11 @@ options:
   domain:
     description:
       - The domain is a domain name of the form com.companyname.appname.
-    required: false
     default: NSGlobalDomain
   host:
     description:
       - The host on which the preference should apply. The special value "currentHost" corresponds to the
         "-currentHost" switch of the defaults commandline tool.
-    required: false
-    default: null
     version_added: "2.1"
   key:
     description:
@@ -43,24 +40,19 @@ options:
   type:
     description:
       - The type of value to write.
-    required: false
     default: string
     choices: [ "array", "bool", "boolean", "date", "float", "int", "integer", "string" ]
   array_add:
     description:
       - Add new elements to the array for a key which has an array as its value.
-    required: false
-    default: false
-    choices: [ "true", "false" ]
+    type: bool
+    default: 'no'
   value:
     description:
       - The value to write. Only required when state = present.
-    required: false
-    default: null
   state:
     description:
       - The state of the user defaults
-    required: false
     default: present
     choices: [ "present", "absent" ]
 notes: