Updates POST comment.

subiquity/common/apidef.py

@@ -409,11 +409,7 @@ class API:
 
     class active_directory:
         def GET() -> Optional[ADConnectionInfo]: ...
-        # POST must validate the payload before configuring the controller,
-        # which may contain several errors as described in [ADValidationResult]
-        # simultaneously - such as invalid chars on the admin name and DC name
-        # starting with a hyphen or a dot. Thus this must returns a List
-        # of errors [ADValidationResult.OK] on success.
+        # POST expects input validated by the check methods below:
         def POST(data: Payload[ADConnectionInfo]) -> None: ...
 
         class check_domain_name: