iio: documentation: light: Add veml6030 sysfs documentation

The driver for veml6030 light sensor provides sysfs
entries like configuring cutoff for interrupt. This
commit document them.
Signed-off-by: Rishi Gupta <gupt21@gmail.com>
Signed-off-by: Jonathan Cameron <Jonathan.Cameron@huawei.com>

Documentation/ABI/testing/sysfs-bus-iio

@@ -753,6 +753,8 @@ What:		/sys/.../events/in_illuminance0_thresh_falling_value
 what:		/sys/.../events/in_illuminance0_thresh_rising_value
 what:		/sys/.../events/in_proximity0_thresh_falling_value
 what:		/sys/.../events/in_proximity0_thresh_rising_value
+What:		/sys/.../events/in_illuminance_thresh_rising_value
+What:		/sys/.../events/in_illuminance_thresh_falling_value
 KernelVersion:	2.6.37
 Contact:	linux-iio@vger.kernel.org
 Description:
@@ -972,6 +974,7 @@ What:		/sys/.../events/in_activity_jogging_thresh_rising_period
 What:		/sys/.../events/in_activity_jogging_thresh_falling_period
 What:		/sys/.../events/in_activity_running_thresh_rising_period
 What:		/sys/.../events/in_activity_running_thresh_falling_period
+What:		/sys/.../events/in_illuminance_thresh_either_period
 KernelVersion:	2.6.37
 Contact:	linux-iio@vger.kernel.org
 Description:
@@ -1715,3 +1718,11 @@ Description:
 		Mass concentration reading of particulate matter in ug / m3.
 		pmX consists of particles with aerodynamic diameter less or
 		equal to X micrometers.
+
+What:		/sys/bus/iio/devices/iio:deviceX/events/in_illuminance_period_available
+Date:		November 2019
+KernelVersion:	5.4
+Contact:	linux-iio@vger.kernel.org
+Description:
+		List of valid periods (in seconds) for which the light intensity
+		must be above the threshold level before interrupt is asserted.