add device Heltec HRI-4851L RS485/modbus to LoRaWAN converter to model list

[g6094199]

its an esp32 with sx1262

Heltec HRI-4851L

and supportes lorawan 1.0.2 rev b

[KrishnaIyer]

@g6094199: Device information for the repository is provided by the manufacturer. If you're not associated with Heltec and are requesting that this device be added to the repo, we'll need to contact someone from there.