metrics: update metrics guide transaction (#5437)
metrics: update metrics guide transaction (#5437)

* update tidb metrics transaction

* Update grafana-tidb-dashboard.md

Co-authored-by: sev7ndayyoo <58c447504617079edd1818ce73e374166afb6497@users.noreply.github.com>
Co-authored-by: TomShawn <3d0966147538bc5ab020e8dffa2c0b746f9728a6@users.noreply.github.com>
pingcap/docs-cn,pingcap/docs-cn