docs: iio: fix grammatical error

Clarify the instruction for disabling autocalibration by adding the word
"by"

Signed-off-by: Ivin Joel Abraham <ivinjabraham@gmail.com>
Link: https://patch.msgid.link/20241002100341.110435-1-ivinjabraham@gmail.com


Signed-off-by: Jonathan Cameron <Jonathan.Cameron@huawei.com>