docs: replace deprecated failValidationError()

Author: kenjis

user_guide_src/source/outgoing/api_responses/002.php

@@ -24,8 +24,8 @@
 // Resource Not Found
 $this->failNotFound($description);
 
-// Data did not validate
-$this->failValidationError($description);
+// Data was not validated
+$this->failValidationErrors($errors);
 
 // Resource already exists
 $this->failResourceExists($description);