Update zpool-features.7 for grub2 compatibility list updates

This commit updates zpool-features.7 man page to add newly added
zpool features to grub2 compatibility list.

Reviewed-by: Alexander Motin <mav@FreeBSD.org>
Reviewed-by: Brian Behlendorf <behlendorf1@llnl.gov>
Signed-off-by: Umer Saleem <usaleem@ixsystems.com>
Closes #15505