Add note for codemod

Author: jerelmiller

docs/source/migrating/apollo-client-4-migration.mdx

@@ -93,6 +93,12 @@ These changes may require code refactoring depending on your usage.
 
 To ease the migration process, we have provided a codemod that automatically updates your codebase.
 
+<Note>
+
+The codemod doesn't update your code with every breaking change. We recommend reading through the full migration guide for any additional changes that need refactoring.
+
+</Note>
+
 This codemod runs modifications in the following order:
 
 <ol><li>