zfs native encryption best practices on RELENG13

[mike tancsa]

Starting to play around with RELENG_13 and wanted explore ZFS' built in
encryption.  Is there a best practices doc on how to do full disk
encryption anywhere thats not GELI based  ?  There are lots for 
GELI,
but nothing I could find for native OpenZFS encryption on FreeBSD

i.e box gets rebooted, enter in passphrase to allow it to boot kind of
thing from the boot loader prompt ?

    ---Mike