Our existing subscription only triggers if someone else uses the `importPerson` mutation to trigger the subscription event - what if we want to let clients know whenever a row is added to our `people` table? Maybe it's added by another service, or something.
In this branch we're using PostgreSQL triggers and stored procedures to send notifications whenever a row is added to the `people` table and we're using `Postgrex.Notifications` to subscribe to them. A substantial portion of the code for this example comes from [this hacker noon post](https://hackernoon.com/get-notified-of-user-signups-and-plan-changes-automatically-using-postgres-phoenix-pubsub-e67d061b04bc).