Added pin maps

[matthias-bs]

No description provided.

[jgromes]

Thank you for the contribution! Have these pin maps been tested, or are they just from the documentation?

Also, this note #pragma message ("Connect DIO1 to GPIO33!") is a bit strange. I gather that in your setup, you conencted DIO1 to pin 33. However, DIO1 is not required for LoRaWAN, so it can be replaced with RADIOLIB_NC - and no hardware modification will be necessary.

[matthias-bs]

Those pin maps are tried and tested with https://github.com/matthias-bs/BresserWeatherSensorTTN (based on Arduino LMIC - therefore DIO1 was needed. I thought RadioLib would need it, too.

[jgromes]

based on Arduino LMIC - therefore DIO1 was needed

I don't think so, RadioLib needs just one of the DIO pins for SX127x/6x to detect packet being received. We're not using CAD to detect when the LoRaWAN gateway is sending a message, just a simple delay and receive with timeout. So I think that note should be removed and RADIOLIB_NC should be used instead of GPIO33.

[matthias-bs]

Modified as suggested.

[jgromes]

Looks good - merged, thanks!