More Fine Grained Control Of Bootloader Section

[FoamyGuy]

The bootloader section currently has the ability to be set on a per-port basis. But in some cases there are different devices within the same port that have differing procedures for entering the bootloader. One cast that I know of for certain is the M5stack Cardputer. The page currently includes the default instructions of double pressing the reset button, but on this device it seems the way to enter the UF2 bootloader is press and release the reset button, then press and release the G0 button (BOOT button).

The text does make reference to the fact that some devices could be different and to consul the relevant documentation, but it would be nice to have the option for the board.md file to include some custom instructions for devices that have non-default entry procedure.