Update .gitignore list for generated scrub cron file

Signed-off-by: Nathan Scott <nathans@debian.org>
Reviewed-by: Darrick J. Wong <darrick.wong@oracle.com>
Reviewed-by: Eric Sandeen <sandeen@redhat.com>
Signed-off-by: Eric Sandeen <sandeen@sandeen.net>

diff --git a/.gitignore b/.gitignore
index d887451..9d92eaf 100644
--- a/.gitignore
+++ b/.gitignore
@@ -71,6 +71,7 @@
 /scrub/xfs_scrub
 /scrub/xfs_scrub@.service
 /scrub/xfs_scrub_all
+/scrub/xfs_scrub_all.cron
 /scrub/xfs_scrub_all.service
 /scrub/xfs_scrub_fail@.service