kernel-parameters.txt : watchdog.txt should be wdt.txt

Documentation/watchdog/watchdog.txt does not exist, it is Documentation/watchdog/wdt.txt
Signed-off-by: NGabriel Craciunescu <nix.or.die@googlemail.com>
Signed-off-by: NAndrew Morton <akpm@linux-foundation.org>
Signed-off-by: NLinus Torvalds <torvalds@linux-foundation.org>

Documentation/kernel-parameters.txt

@@ -1922,7 +1922,7 @@ and is between 256 and 4096 characters. It is defined in the file
 			See header of drivers/scsi/wd7000.c.
 
 	wdt=		[WDT] Watchdog
-			See Documentation/watchdog/watchdog.txt.
+			See Documentation/watchdog/wdt.txt.
 
 	xd=		[HW,XT] Original XT pre-IDE (RLL encoded) disks.
 	xd_geo=		See header of drivers/block/xd.c.