docs/zh_CN: Add sched-capacity Chinese translation

Translate scheduler/sched-capacity.rst into Chinese.
Signed-off-by: Tang Yizhou <tangyizhou@huawei.com>
Reviewed-by: Yanteng Si <siyanteng@loongson.cn>
Reviewed-by: Alex Shi <alexs@kernel.org>
Link: https://lore.kernel.org/r/20211213095945.17011-2-tangyizhou@huawei.comSigned-off-by: Jonathan Corbet <corbet@lwn.net>

Documentation/translations/zh_CN/scheduler/index.rst

@@ -20,6 +20,7 @@ Linux调度器
     completion
     sched-arch
     sched-bwc
+    sched-capacity
 
 
 TODOList:
@@ -28,7 +29,6 @@ TODOList:
     sched-deadline
     sched-design-CFS
     sched-domains
-    sched-capacity
     sched-energy
     sched-nice-design
     sched-rt-group