NEWS: mention removal of obsolete commands

NEWS: mention removal of obsolete commands

Removed remaining support for various commands, like advice for
migrating old-style TAP declarations.

The documentation no longer describes them either ... so if users have
been delaying config updates, they may need to consult older releases.

ALL this stuff has been clearly marked as "do not use" for at least a
year now, so anyone still using it hasn't been holding up their end.

Signed-off-by: David Brownell <dbrownell@users.sourceforge.net>