Update Waveshare S3 Zero pins.c to add BOOT button

[Timeline8]

Currently the BOOT button, which is labeled simply as "B" on the silkscreen, is not defined in the BOARD module of Circuit{Python and therefore to use this button as an input requires

import microcontroller
from digitalio import DigitalInOut
button = DigitalInOut(microcontroller.pin.GPIO0)

This change adds "BUTTON" & "D0" aliases for the GPIO0 pin.

For reference, Waveshare ESP32-S3-Zero schematic is here: https://files.waveshare.com/wiki/ESP32-S3-Zero/ESP32-S3-Zero-Sch.pdf

[tannewt]

One small thing

[tannewt]

Fine with me. Thanks!