Include codegen crate name in generated file header
diff --git a/src/gen/visit.rs b/src/gen/visit.rs
index e449a0b..3e43914 100644
--- a/src/gen/visit.rs
+++ b/src/gen/visit.rs
@@ -1,4 +1,5 @@
-// THIS FILE IS AUTOMATICALLY GENERATED; DO NOT EDIT
+// This file is @generated by syn-internal-codegen.
+// It is not intended for manual editing.
 
 #![cfg_attr(feature = "cargo-clippy", allow(trivially_copy_pass_by_ref))]
 #[cfg(any(feature = "full", feature = "derive"))]