Remove $FreeBSD$: one-line sh pattern

Remove /^\s*#[#!]?\s*\$FreeBSD\$.*$\n/

In followup to r340406, remove doc from the EXTRA_DISTRIBUTIONS
list and remaining references from the script used to create the
MANIFEST file used by bsdinstall(8).

No MFC is planned at this time.

Sponsored by: The FreeBSD Foundation

The roff ascii.gz documentation installed to /usr/share/doc
was removed in r318881 when roff was removed from the base
system.

This results in the doc.txz distribution set containing a
single directory (./) which is empty.

Remove the "Additional documentation" option from the menu
selection of bsdinstall(8), as the plain-text documentation
installed in /usr/share/doc is installed as part of the
packageworld target.

The doc entry has not been removed from EXTRA_DISTRIBUTIONS
in Makefile.inc1, in case its removal triggers an issue with
freebsd-update(8), which is currently aware of the world/doc
component, so the empty doc.txz continues to be created as
a precaution.

Noticed by: rgrimes
MFC after: 2 days
MFC before: 12.0-RC1
Sponsored by: The FreeBSD Foundation

Change installer default to not install ports tree

Reviewed by: gjb, dteske, allanjude, bdrewery, mat
Approved by: gjb
Differential Revision: https://reviews.freebsd.org/D14064

Merge ^/projects/release-install-debug:

- Rework MANIFEST generation and parsing via bsdinstall(8).
- Allow selecting debugging distribution sets during install.
- Rework bsdinstall(8) to fetch remote debug distribution sets
when they are not available on the local install medium.
- Allow selecting additional non-GENERIC kernels during install.
At present, GENERIC is still required, and installed by default.

Tested with: head@r293203
Sponsored by: The FreeBSD Foundation

Step 1 of eliminating the "games" distribution: Move binaries to /usr/bin;
update paths; and include everything in the "base" distribution.

The "games" distribution being optional made sense when there were more
games and we had small disks; but the "games-like" games were moved into
the ports tree a dozen years ago and the remaining "utility-like" games
occupy less than 0.001% of my laptop's small hard drive. Meanwhile every
new user is confronted by the question "do you want games installed" when
they they try to install FreeBSD.

The next steps will be:

2. Removing punch card (bcd, ppt), phase-of-moon (pom), clock (grdc), and
caesar cipher (caesar, rot13) utilities. I intend to keep fortune, factor,
morse, number, primes, and random, since there is evidence that those are
still being used.

3. Merging src/games into src/usr.bin.

This change will not be MFCed.

Reviewed by: jmg
Discussed at: EuroBSDCon
Approved by: gjb (release-affecting changes)

Fix a typo in a comment.

MFC after: 1 week
X-MFC-with: r277837
Sponsored by: The FreeBSD Foundation

Provide a description for the 'tests.txz' distribution
in the MANIFEST file.

Turn off the test suite installation by default.

Tested with: head@r277834
MFC after: 1 week
Sponsored by: The FreeBSD Foundation

Add generation of an installation manifest containing SHA256 checksums as
well as package descriptions and add code in the installer to check the
checksums.