This new sysfs entry is used to interpret ring buffer information,
mainly by Android sensor HAL.
It expand to all sensors, the documentation about 'id' we can found
in Documentation/ABI/testing/sysfs-bus-iio-cros-ec.

Also fix typo in docs, I replace 'Septembre' by 'September'.
Signed-off-by: Gwendal Grignou <gwendal@chromium.org>
Signed-off-by: Fabien Lahoudere <fabien.lahoudere@collabora.com>
Signed-off-by: Jonathan Cameron <Jonathan.Cameron@huawei.com>