tidb_ddl_reorg_max_write_speed: add the support info of v6.5.12 (#19897) (#19932)

Author: ti-chi-bot

system-variables.md

@@ -1471,7 +1471,7 @@ mysql> SELECT job_info FROM mysql.analyze_jobs ORDER BY end_time DESC LIMIT 1;
 - 可选值：`PRIORITY_LOW`、`PRIORITY_NORMAL`、`PRIORITY_HIGH`
 - 这个变量用来设置 `ADD INDEX` 操作 `re-organize` 阶段的执行优先级，可设置为 `PRIORITY_LOW`/`PRIORITY_NORMAL`/`PRIORITY_HIGH`。
 
-### `tidb_ddl_reorg_max_write_speed` <span class="version-mark">从 v7.5.5 版本开始引入</span>
+### `tidb_ddl_reorg_max_write_speed` <span class="version-mark">从 v6.5.12 和 v7.5.5 版本开始引入</span>
 
 - 作用域：GLOBAL
 - 是否持久化到集群：是