docs: fix quota refresh interval description (#6480)

Author: Xuyuchao-juice

docs/en/guide/quota.md

@@ -120,7 +120,7 @@ juicefs config $METAURL --inodes 100000
 ```
 
 :::tip
-The client reads the latest storage quota settings from the metadata engine every 60 seconds to update the local settings, and this frequency may cause other mount points to take up to 60 seconds to update the quota setting.
+The client reads the latest storage quota settings from the metadata engine periodically to update the local settings. The refresh interval is controlled by the `--heartbeat` option (default: 12 seconds). Other mount points may take up to the heartbeat interval to update the quota setting.
 :::
 
 ## Directory quota {#directory-quota}

docs/zh_cn/guide/quota.md

@@ -120,7 +120,7 @@ juicefs config $METAURL --inodes 100000
 ```
 
 :::tip 提示
-客户端每 60 秒从元数据引擎读取一次最新的文件系统存储限额设置来更新本地的设置，这个时间频率可能会造成其他挂载点最长需要 60 秒才能完成限额设置的更新。
+客户端会定期从元数据引擎读取最新的文件系统存储限额设置来更新本地的设置。刷新间隔由 `--heartbeat` 参数控制（默认值：12 秒）。其他挂载点可能需要等待最多一个 heartbeat 间隔时间才能完成限额设置的更新。
 :::
 
 ## 目录配额 {#directory-quota}