How to add new device on hassio

I’ve looked everywhere but i can’t find any good documentation on how to add a new device on hassio.

is it possible to access the zigbee2mqtt devices.js etc through a filesystem so i can edit them with a texteditor like sublime instead of via the terminal?

I get to the point where I need to edit it with docker exec -it 87df0de79efd bash but thats where my knowledge ends

Automatic doscovery should do it after you have paired device with mqtt broker, i believe.