add note about ck to v5 migration guide

Author: Cvolton

tutorials/migrate-v5.md

@@ -404,4 +404,7 @@ should now be written as:
 `path` setting type has been removed, use `file` instead, the behavior is identical.
 
 ## SceneManager replaced by OverlayManager
-SceneManager is gone now. Use OverlayManager. It's a CCNode. You use it: like any other CCNode.
+SceneManager is gone now. Use OverlayManager. It's a CCNode. You use it: like any other CCNode.
+
+## Custom Keybinds
+If your mod depends on Custom Keybinds, well, it doesn't anymore! See the [keybind setting documentation](mods/settings/#keybind) for more info including migration from the old system.