iio: drop wrong reference from Kconfig

The documentation lives in drivers/staging/iio/Documentation, but
according to Jonathan it's obsolete and needs fixing.

Signed-off-by: Jiri Kosina <jkosina@suse.cz>
Acked-by: Jonathan Cameron <jic23@kernel.org>
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
diff --git a/drivers/iio/Kconfig b/drivers/iio/Kconfig
index 56eecef..2ec93da 100644
--- a/drivers/iio/Kconfig
+++ b/drivers/iio/Kconfig
@@ -8,8 +8,7 @@
 	help
 	  The industrial I/O subsystem provides a unified framework for
 	  drivers for many different types of embedded sensors using a
-	  number of different physical interfaces (i2c, spi, etc). See
-	  Documentation/iio for more information.
+	  number of different physical interfaces (i2c, spi, etc).
 
 if IIO