update zh-cn/application-dev/task-management/reminder-agent-development.md.

Signed-off-by: N葛亚芳 <geyafang@huawei.com>

zh-cn/application-dev/task-management/reminder-agent-development.md

@@ -175,3 +175,9 @@
        console.log("cancelReminder code: " + error.code + ", message: " + error.message);
    };
    ```
+
+## 相关实例
+
+基于后台代理提醒的开发，有以下相关实例可供参考：
+
+- [闹钟（ArkTS）（API9）](https://gitee.com/openharmony/codelabs/tree/master/CommonEventAndNotification/AlarmClock)
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