iio: add ABI documentation for scaled pressure

Signed-off-by: NVlad Dogaru <vlad.dogaru@intel.com>
Reviewed-by: NDaniel Baluta <daniel.baluta@intel.com>
Signed-off-by: NJonathan Cameron <jic23@kernel.org>

Documentation/ABI/testing/sysfs-bus-iio

@@ -200,6 +200,13 @@ Description:
 		Raw pressure measurement from channel Y. Units after
 		application of scale and offset are kilopascal.
 
+What:		/sys/bus/iio/devices/iio:deviceX/in_pressureY_input
+What:		/sys/bus/iio/devices/iio:deviceX/in_pressure_input
+KernelVersion:	3.8
+Contact:	linux-iio@vger.kernel.org
+Description:
+		Scaled pressure measurement from channel Y, in kilopascal.
+
 What:		/sys/bus/iio/devices/iio:deviceX/in_humidityrelative_raw
 KernelVersion:	3.14
 Contact:	linux-iio@vger.kernel.org