Staging: iio: Add mailing list to the TODO file.

As suggested by Charles Clement
Signed-off-by: NJonathan Cameron <jic23@cam.ac.uk>
Signed-off-by: NGreg Kroah-Hartman <gregkh@suse.de>

drivers/staging/iio/TODO

@@ -66,4 +66,4 @@ Documentation
 2) Some device require indvidual docs.
 
 Contact: Jonathan Cameron <jic23@cam.ac.uk>.
-Mailing list: LKML.
+Mailing list: linux-iio@vger.kernel.org