The changes screen.
Pilot cList shows you what changed the first time you launch the app with a new version. If you want to see the change list again, tap the ❓button on the home screen then select Changes button.
The ?➠☁️ button (sync) has been added to the main screen toolbar. To synchronize your lists, simply tap this button or swipe down on your list.
From Apple:Core Data iCloud Deprecation.
As of iOS 10.0; Core Data’s iCloud integration feature has been deprecated. Apps will continue to work. There are no changes to or removal of the functionality in iOS 10. Historically, deprecated symbols remain functional for a considerable period of time before removal. The service pieces are not effected in any way. If and when the deprecated APIs are disabled in some future OS version, applications running on iOS 9 or 10 will continue to work. One in a Million Apps LLC used Apple’s Core Data over iCloud to synchronize lists between devices. We are being proactive and replaced the functionality that Apple will eventually phase out with a new mechanism to sync lists.