docs: update migration_guide_gov3_to_gov4.md

Clarify where to migrate the controllers to.

docs/book/src/migration/migration_guide_gov3_to_gov4.md

@@ -103,7 +103,7 @@ These files have not been modified by the new plugin, so you should be able to r
 
 ### Migrate the Controllers
 
-Now, let's migrate the controller code from `controllers/cronjob_controller.go` in our old project to the new one.
+Now, let's migrate the controller code from `controllers/cronjob_controller.go` in our old project to `internal/controller/cronjob_controller.go` in the new one.
 
 ## Migrate the Webhooks
 
@@ -158,4 +158,4 @@ fine.
 [controller-runtime]: https://github.com/kubernetes-sigs/controller-runtime/releases
 [multi-group]: multi-group.md
 [manually-upgrade]: manually_migration_guide_gov3_to_gov4.md
-[project-file]: ../reference/project-config.md
+[project-file]: ../reference/project-config.md