iio: Move documentation of iio-trig-sysfs to ABI/testing

iio-trig-sysfs has left staging with commit e64e7d5c

Signed-off-by: Peter Meerwald <pmeerw@pmeerw.net>
Signed-off-by: Jonathan Cameron <jic23@kernel.org>
diff --git a/drivers/staging/iio/Documentation/sysfs-bus-iio-trigger-sysfs b/Documentation/ABI/testing/sysfs-bus-iio-trigger-sysfs
similarity index 100%
rename from drivers/staging/iio/Documentation/sysfs-bus-iio-trigger-sysfs
rename to Documentation/ABI/testing/sysfs-bus-iio-trigger-sysfs