media: media-ioc-enum-links.rst: improve pad index description

Make it clearer that the index starts at 0.
Signed-off-by: NHans Verkuil <hansverk@cisco.com>
Signed-off-by: NMauro Carvalho Chehab <mchehab+samsung@kernel.org>

Documentation/media/uapi/mediactl/media-ioc-enum-links.rst

@@ -92,7 +92,7 @@ returned during the enumeration process.
 
     *  -  __u16
        -  ``index``
-       -  0-based pad index.
+       -  Pad index, starts at 0.
 
     *  -  __u32
        -  ``flags``