how to verify firmware version of boards

[Prx]

I suggest to add how to verify / control the firmware version of boards on doc page https://docs.pycom.io/pytrackpysense/installation/firmware
For my own, I am mainly interested in the one of expansion board v3.
thanks

[peterv]

For a Pytrack Pytrack().read_fw_version() works, but I don't know how to do that for the expansion board.