Add tsys02d meas-spec driver support

Support for TSYS02D temperature sensor

Signed-off-by: Ludovic Tancerel <ludovic.tancerel@maplehightech.com>
Signed-off-by: Jonathan Cameron <jic23@kernel.org>
diff --git a/Documentation/ABI/testing/sysfs-bus-iio-meas-spec b/Documentation/ABI/testing/sysfs-bus-iio-meas-spec
new file mode 100644
index 0000000..6d47e54
--- /dev/null
+++ b/Documentation/ABI/testing/sysfs-bus-iio-meas-spec
@@ -0,0 +1,7 @@
+What:           /sys/bus/iio/devices/iio:deviceX/battery_low
+KernelVersion:  4.1.0
+Contact:        linux-iio@vger.kernel.org
+Description:
+                Reading returns either '1' or '0'. '1' means that the
+                battery level supplied to sensor is below 2.25V.
+                This ABI is available for tsys02d, htu21, ms8607