Document r259141, jail(8) ipv6 allocation startup bug.

Sponsored by:	The FreeBSD Foundation
Document r264438, mdconfig(8) rc.conf(5) listing is no longer
required to be sequential.

Sponsored by:	The FreeBSD Foundation
Document r262566, sshd(8) startup script creates ed25519 keys
if ENOENT on startup.

Sponsored by:	The FreeBSD Foundation