There are 2 ways you can be notified about changes to your Shelf:
Email alert
In-app notification
To adjust how you’re notified of changes, click on the Profile Settings option in the dropdown menu that is accessed by clicking on your Avatar. Once here, you’ll see a tab on the left side panel called Notifications.
Here you can decide to receive email alerts, in-app notifications, both, or neither for a variety of actions within Shelf.