Was incorrectly added as 7MB for an 8MB SPI flash, but this board has a
16MB chip, not 8MB, so it should be 15MB leaving 1MB for MicroPython.
Thanks to @robert-hh
This will be used by https://micropython.org/download/ to generate the
full listing of boards and firmware files.
Optionally supports a board.md for additional customisation of the
download page, as well as deploy.md for flashing instructions.
Signed-off-by: Jim Mussared <jim.mussared@gmail.com>