Documentation: cpu-idle-cooling: Fix diagram for 33% duty cycle

Signed-off-by: Sergey Vidishev <sergeyv@yandex-team.ru>
Signed-off-by: Daniel Lezcano <daniel.lezcano@linaro.org>
Link: https://lore.kernel.org/r/2374188.AZIXMmL6Zy@sergeyv-box

Documentation/driver-api/thermal/cpu-idle-cooling.rst

@@ -105,7 +105,7 @@ and this variation will modulate the cooling effect.
        idle  <-------------->
                 running
 
-      <----------------------------->
+      <--------------------->
           duty cycle 33%