iio: Add intensity including ir and both modifiers to ABI documentation ex-post

intensity has been in use for a long time but never documented
it is beneficial to document what this is supposed to be
Signed-off-by: NPeter Meerwald <pmeerw@pmeerw.net>
Signed-off-by: NJonathan Cameron <jic23@kernel.org>

Documentation/ABI/testing/sysfs-bus-iio

@@ -895,6 +895,16 @@ Description:
 		on-chip EEPROM. After power-up or chip reset the device will
 		automatically load the saved configuration.
 
+What:		/sys/.../iio:deviceX/in_intensityY_raw
+What:		/sys/.../iio:deviceX/in_intensityY_ir_raw
+What:		/sys/.../iio:deviceX/in_intensityY_both_raw
+KernelVersion:	3.4
+Contact:	linux-iio@vger.kernel.org
+Description:
+		Unit-less light intensity. Modifiers both and ir indicate
+		that measurements contains visible and infrared light
+		components or just infrared light, respectively.
+
 What:		/sys/.../iio:deviceX/in_intensity_red_integration_time
 What:		/sys/.../iio:deviceX/in_intensity_green_integration_time
 What:		/sys/.../iio:deviceX/in_intensity_blue_integration_time