kconfig: mention 'hibernation' not just swsusp

Clarify that "software suspend" is what's called "hibernation" in most user
interfaces, shrinking a terminology gap.  (Examples include Gnome and
MS-Windows.)

Also provide a more succinct description of what it does, so you won't have
to read the whole novel in Kconfig; and highlights just why the lack of
BIOS requirements for swsusp are a big deal.

Signed-off-by: David Brownell <dbrownell@users.sourceforge.net>
Acked-by: "Rafael J. Wysocki" <rjw@sisk.pl>
Acked-by: Pavel Machek <pavel@ucw.cz>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>