br: link to BR monitoring and alert

[Oreoxmt]

What is changed, added or deleted? (Required)

Add link to BR monitoring and alert

Which TiDB version(s) do your changes apply to? (Required)

Tips for choosing the affected version(s):

By default, CHOOSE MASTER ONLY so your changes will be applied to the next TiDB major or minor releases. If your PR involves a product feature behavior change or a compatibility change, CHOOSE THE AFFECTED RELEASE BRANCH(ES) AND MASTER.

For details, see tips for choosing the affected versions (in Chinese).

• master (the latest development version)
• v8.2 (TiDB 8.2 versions)
• v8.1 (TiDB 8.1 versions)
• v8.0 (TiDB 8.0 versions)
• v7.6 (TiDB 7.6 versions)
• v7.5 (TiDB 7.5 versions)
• v7.1 (TiDB 7.1 versions)
• v6.5 (TiDB 6.5 versions)
• v6.1 (TiDB 6.1 versions)
• v5.4 (TiDB 5.4 versions)
• v5.3 (TiDB 5.3 versions)
• v5.2 (TiDB 5.2 versions)
• v5.1 (TiDB 5.1 versions)

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[YuJuncen]

要不要考虑在上面单独加一段？这样更加明显一些。

## 任务监控及告警

如前文所提到的，日志备份在任务下发之后，各个 TiKV 节点会持续往外部存储写入数据。此时你可以通过 TiKV Details 面板下，Log Backup 行中看到相应的监控数据。

此外，如果想要在指标异常时获得通知，你可以参考[日志备份告警配置指南](/br/br-monitoring-and-alert.md#日志备份告警)来配置 Alert Manager。

[Oreoxmt]

/cc @YuJuncen