Bayer data handling has the LSBits reversed #462
Description
In https://github.com/waveform80/picamera/blob/master/docs/examples/bayer_data.py#L55 when describing the 2 least sig bits from the 4 pixels, the order is reversed.
The correct order is:
# byte 1 byte 2 byte 3 byte 4 byte 5
# AAAAAAAA BBBBBBBB CCCCCCCC DDDDDDDD DDCCBBAA
as confirmed by https://linuxtv.org/downloads/v4l-dvb-apis-new/uapi/v4l/pixfmt-srggb10p.html or the CSI-2 spec.