Document Meshtastic compatibility (alternative firmware)

[jurgelenas]

Radiomaster Bandit Nano

https://radiomasterrc.com/products/bandit-nano-expresslrs-rf-module

Radiomaster Bandit Micro

https://github.com/meshtastic/firmware/tree/develop/variants/esp32/radiomaster_900_bandit_micro

BetaFPV 2.4 GHz Micro

https://github.com/meshtastic/firmware/tree/develop/variants/esp32/betafpv_2400_tx_micro

BetaFPV 900 MHz Nano

https://github.com/meshtastic/firmware/tree/develop/variants/esp32/betafpv_900_tx_nano