T-Beam button - pin 13

A while back there was support added for an external button (momentary switch…) for the T-Beam.
I have all mine wired up to pin 13 and ground. The code has moved on quite a bit since then. Could someone point me to the docs / explain how I get these buttons working again. Is it simply a software setting?
Tx

You will need to define the pin that you are using. Device Configuration | Meshtastic

You can do this in either app by going to Settings > Device or via CLI using device.button_gpio