Missing doris_be_cpu Monitoring Metric Field

Path:/zh-CN/docs/2.0/admin-manual/maint-monitor/monitor-metrics/metrics

Description
When checking monitoring metrics related to Doris BE (Backend), the doris_be_cpu metric field is not found. This metric is crucial for monitoring CPU resource usage of BE nodes and troubleshooting performance bottlenecks (such as whether slow queries or task backlogs are caused by CPU saturation). However, this field is currently absent from the set of accessible/queryable BE monitoring metrics.
Environment Information
Doris version: doris-2.1.7-rc03-443e87e203

Open the monitoring metrics page at /zh-CN/docs/2.0/admin-manual/maint-monitor/monitor-metrics/metrics and review the Doris BE metric list. Verify whether doris_be_cpu is absent from the documented accessible/queryable metrics, then update the page so the CPU metric is represented; the page should clearly include doris_be_cpu when finished.

Written by the indexing model from the issue text.