Build a Weather Station with Elixir and Nerves: Phoenix IP address binding question

I may doing something wrong, but I had to edit the WeatherTrackerWeb.Endpoint to change the IP to {0, 0, 0, 0} (as suggested in a boilerplate comment) in dev.exs. I’m not sure if I missed it somewhere in the book, or if there’s another place the endpoint IP should be specified.