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