sched/doc: Update yield_task description in sched-design-CFS

The yield_task description referenced the long-removed compat_yield
sysctl and described the function as a dequeue/enqueue cycle. Update
it to reflect current behavior: yielding the CPU by moving the
current task's position back in the runqueue.

Sync zh_CN and sp_SP translations.

Signed-off-by: fangqiurong <fangqiurong@kylinos.cn>
Signed-off-by: Jonathan Corbet <corbet@lwn.net>
Message-ID: <20260403055806.358921-1-user@fqr-pc>

Documentation/scheduler/sched-design-CFS.rst

@@ -183,9 +183,8 @@ This is the (partial) list of the hooks:
 
  - yield_task(...)
 
-   This function is basically just a dequeue followed by an enqueue, unless the
-   compat_yield sysctl is turned on; in that case, it places the scheduling
-   entity at the right-most end of the red-black tree.
+   This function yields the CPU by moving the currently running task's position back
+   in the runqueue, so that other runnable tasks get scheduled first.
 
  - wakeup_preempt(...)
 

Documentation/translations/sp_SP/scheduler/sched-design-CFS.rst

@@ -198,9 +198,9 @@ Esta es la lista parcial de llamadas:
 
  - yield_task(...)
 
-   Esta función es básicamente desencolar, seguido por encolar, a menos que
-   sysctl compat_yield esté activado; en ese caso, sitúa la entidad a gestionar
-   en la parte más hacia la derecha del árbol rojo-negro.
+   Esta función cede la CPU desplazando la posición de la tarea actualmente
+   en ejecución hacia atrás en la cola de ejecución, para que otras tareas
+   ejecutables sean planificadas primero.
 
  - check_preempt_curr(...)
 

Documentation/translations/zh_CN/scheduler/sched-design-CFS.rst

@@ -144,8 +144,8 @@ array）。
 
  - yield_task(...)
 
-   这个函数的行为基本上是出队，紧接着入队，除非compat_yield sysctl被开启。在那种情况下，
-   它将调度实体放在红黑树的最右端。
+   此函数通过将当前任务在运行队列中的位置后移来让出 CPU，
+   使得其他可运行的任务优先被调度。
 
  - wakeup_preempt(...)