文档新增需求，请按照下方模板反馈：
- 需求类型：新增文档
- 需求背景：比如缺少哪部分文档，对使用有什么影响
- 期望增加哪些组件或者功能的文档，加到现有文档的哪个位置
文档中缺少对新参数的解释，
mysql> select version();
+--------------------+
| version() |
+--------------------+
| 8.0.11-TiDB-v7.5.0 |
+--------------------+
1 row in set (0.00 sec)
mysql> select * from information_schema.cluster_config where `key` like '%copr-req-timeout%';
+------+-------------------+------------------------------+-------------+
| TYPE | INSTANCE | KEY | VALUE |
+------+-------------------+------------------------------+-------------+
| tidb | 192.168.8.92:4000 | tikv-client.copr-req-timeout | 60000000000 |
+------+-------------------+------------------------------+-------------+
1 row in set (0.04 sec)