14.0 relnotes: recommend updating EFI boot loader when booting UFS

UFS root file systems do not have the same issues as ZFS for the
boot loader, but the boot loader should still be updated. Generalize
the section on updating the ESP. ZFS must be done before zpool update,
UFS should be done.

Discussed with: imp
Differential Revision: https://reviews.freebsd.org/D42549