Misleading documentation of UpdateImage in python lib.

[Tomas-kubicek]

HI, the comment
"""
Updates the pixel values of a specified image region and a specified set of channels.
The image parameter must be laid out in row-major format, i.e. from most to least
significant: [col][row][channel], where the channel axis is optional.
"""
in the update funtion is wrong. Row major ordering is [row][col][channel]

[Thomas Müller]

Good catch, thank you! Fixed on master.