x86, documentation: nmi_watchdog=2 works on x86_64

Signed-off-by: Marcin Slusarz <marcin.slusarz@gmail.com>
Cc: Peter Zijlstra <a.p.zijlstra@chello.nl>
Signed-off-by: Ingo Molnar <mingo@elte.hu>
1 file changed