docs: watchdog: Fix build error.

make htmldocs fails due to missing blank line following header.
Signed-off-by: Jerry Hoemann <jerry.hoemann@hpe.com>
Reviewed-by: Mauro Carvalho Chehab <mchehab+samsung@kernel.org>
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/watchdog-parameters.rst

@@ -12,6 +12,7 @@ providing kernel parameters for builtin drivers versus loadable
 modules.
 
 -------------------------------------------------
+
 watchdog core:
     open_timeout:
 	Maximum time, in seconds, for which the watchdog framework will take
@@ -22,6 +23,7 @@ watchdog core:
 	fallback logic in the bootloader to try something else.
 
 -------------------------------------------------
+
 acquirewdt:
     wdt_stop:
 	Acquire WDT 'stop' io port (default 0x43)