Remove /^\.\\"\s*\$FreeBSD\$$\n/

Similar commit in main:
(cherry picked from commit b2c76c41be32)

RB_ASKNAME is no longer instructions to the boot loader to request a
prompt for which kernel to boot. Instead, it asks for what the root
file system to use. RB_INITNAME is unused, and never has been in
FreeBSD as far as I can tell. Remove it from the documentation and fix
comment. RB_SELFTEST and RB_MINIROOT likewise (though they were
completely undocumented). These last three constants can likely just
be deleted as nothing references them (even to set useless bits).

RB_ASKNAME doesn't actually survive reboot, however, so needs to be
communicated to the bootloader via other means. If the bootloader sets
it, though, it will be honored.

RB_POWERCYCLE instructs the platform to power off and then power back
on a short time later, if that's possible. Otherwise, degrade to the
RB_POWEROFF behavior.

Sponsored by: Netflix

Renumber cluase 4 to 3, per what everybody else did when BSD granted
them permission to remove clause 3. My insistance on keeping the same
numbering for legal reasons is too pedantic, so give up on that point.

Submitted by:	Jan Schaumann <jschauma@stevens.edu>
Pull Request:	https://github.com/freebsd/freebsd/pull/96

MFC after:	1 month
Sponsored by:	The FreeBSD Foundation

BUGS section.

While I'm there also bump Dd date.

MFC after:	2 weeks

Note that the mountlist manipulations are somewhat fragile, and not very
pretty.  The reason for this is to avoid changing vfs_mountroot(), which
is (obviously) rather mission-critical, but not very well documented,
and thus hard to test properly.  It might be possible to rework it to use
its own simple root mount mechanism instead of vfs_mountroot().

Reviewed by:	kib@
MFC after:	1 month
Sponsored by:	The FreeBSD Foundation
Differential Revision:	https://reviews.freebsd.org/D2698

clause.

# If I've done so improperly on a file, please let me know.