docs: leds: ledtrig-oneshot: Fix spelling mistake

It's no comparison, but a "first this, then that" situation.

Signed-off-by: Alexander Dahl <ada@thorsis.com>
Acked-by: Pavel Machek <pavel@ucw.cz>
Signed-off-by: Lee Jones <lee@kernel.org>
Link: https://lore.kernel.org/r/20230418113402.188391-1-ada@thorsis.com

Author: LeSpocky

Documentation/leds/ledtrig-oneshot.rst

@@ -5,7 +5,7 @@ One-shot LED Trigger
 This is a LED trigger useful for signaling the user of an event where there are
 no clear trap points to put standard led-on and led-off settings.  Using this
 trigger, the application needs only to signal the trigger when an event has
-happened, than the trigger turns the LED on and than keeps it off for a
+happened, then the trigger turns the LED on and then keeps it off for a
 specified amount of time.
 
 This trigger is meant to be usable both for sporadic and dense events.  In the