Document EEPROM write-protect pins

[Gadgetoid]

Because our (Pimoroni's) HATs are designed to allow the EEPROM to be programmed directly from a Pi (to save pain and time while testing), they tend to have an EEPROM write-protect pin which is pulled up to 3.3v. Since this pull-up can very easily interfere with functions of other boards, I think it would be a good idea to document at least the write-protect pins of any HATs that have them. Right now Pinout.xyz gives the impression that some pins are free, when they're really not.

Of course it all depends how you wire up HATs, but in this case I think we're better off documenting these pins than not.