mountinfo: fix go doc
mountinfo: fix go doc

Nothing from the doc.go was shown by godoc -- this is because the
comment about the package as a whole should precede the "package
$NAME", and this was broken here because of an empty line.

Signed-off-by: Kir Kolyshkin <3a017b8ddb3f9cf3e4a59978b004111bdeb97f08@gmail.com>

moby/sys