watchdog/hpwdt: Update documentation

Update documentation to explain new module parameter kdumptimeout.
Signed-off-by: Jerry Hoemann <jerry.hoemann@hpe.com>
Reviewed-by: Guenter Roeck <linux@roeck-us.net>
Signed-off-by: Guenter Roeck <linux@roeck-us.net>
Signed-off-by: Wim Van Sebroeck <wim@linux-watchdog.org>

Documentation/watchdog/hpwdt.txt

@@ -33,6 +33,10 @@ Last reviewed: 08/20/2018
                Default value is set when compiling the kernel. If it is set
                to "Y", then there is no way of disabling the watchdog once
                it has been started.
+ kdumptimeout  Minimum timeout in seconds to apply upon receipt of an NMI
+               before calling panic. (-1) disables the watchdog.  When value
+               is > 0, the timer is reprogrammed with the greater of
+               value or current timeout value.
 
  NOTE: More information about watchdog drivers in general, including the ioctl
        interface to /dev/watchdog can be found in