update zh-cn/application-dev/task-management/Readme-CN.md.

Signed-off-by: Nningning <3248127340@qq.com>

zh-cn/application-dev/task-management/Readme-CN.md

-# 后台任务(Background Task)管理
+# 后台任务（Background Task）管理
 
-- 后台任务
+- 后台任务 
   - [后台任务概述](background-task-overview.md)
   - [短时任务开发指导](transient-task-dev-guide.md)
   - [长时任务开发指导](continuous-task-dev-guide.md)
   - [延迟任务开发指导](work-scheduler-dev-guide.md)
-  - [延迟任务回调能力开发指导](workscheduler-extensionability.md)
+  - [延迟任务回调能力开发指导（WorkSchedulerExtensionAbility）](workscheduler-extensionability.md)
   - [申请能效资源开发指导](efficiency-resources-apply-dev-guide.md)
 
 - 后台代理提醒