file: update docs on FileFromJSON validation
Fixes:
@@ -100,7 +100,7 @@ type advFileControl struct {
//
// Callers should always check for a nil-error before using the returned file.
//
-// The File returned may not be valid and callers should confirm with Validate.
+// The File returned may not be valid and an error may be returned from validation.
// Invalid files may be rejected by Financial Institutions or ACH tools.
//
// Date and Time fields in formats: RFC 3339 and ISO 8601 will be parsed and rewritten
