docs/library/machine.I2S.rst: Specify that I2S.shift args are kw-only.
docs/library/machine.I2S.rst: Specify that I2S.shift args are kw-only.

bvernoux/micropython,bvernoux/micropython,adafruit/circuitpython,adafruit/circuitpython,adafruit/circuitpython,bvernoux/micropython,bvernoux/micropython,adafruit/circuitpython,adafruit/circuitpython,bvernoux/micropython,adafruit/circuitpython