Commit ac1f5912 ("kernel/watchdog.c: add sysctl knob
hardlockup_panic") added the hardlockup_panic sysctl, but did not add it
to Documentation/sysctl/kernel.txt.  Add this, and reference it from the
corresponding entry in Documentation/admin-guide/kernel-parameters.txt.
Signed-off-by: NScott Wood <swood@redhat.com>
Acked-by: NChristoph von Recklinghausen <crecklin@redhat.com>
Acked-by: NDon Zickus <dzickus@redhat.com>
Signed-off-by: NJonathan Corbet <corbet@lwn.net>