I've noticed that the built-in cards shown on a contact record show a message to the user when there are no objects in it. For example, the Tickets card says "Use tickets to track all of your customer's questions and requests for help." This is a super useful prompt for new users on how to use the card.
How can a custom card created via the CRM Extensions API provide a similar message? Right now the card seems like it can either show sales objects or just show up blank, which is not ideal.