init/Kconfig: restore CONFIG_BROKEN help text

Linus added it in 2003, it later was removed.  Put it back.

Cc: Anshuman Khandual <anshuman.khandual@arm.com>
Cc: Borislav Betkov <bp@alien8.de>
Cc: David S. Miller <davem@davemloft.net>
Cc: Ingo Molnar <mingo@redhat.com>
Cc: Thomas Gleinxer <tglx@linutronix.de>
Cc: Christophe Leroy <christophe.leroy@csgroup.eu>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>