* docs(kms): describe KMS configuration convergence as implemented
* docs(kms): document the landed KMS metric families and narrow the gaps list
* docs(kms): state that no request field sets the cache metrics switch
* docs(kms): correct the describe_key cache divergence bound
Add a Grafana dashboard for the four KMS backend operation metrics
emitted at the policy choke point, Prometheus alert rules with
conservative default thresholds (pending staging baseline calibration),
and an operations runbook documenting the metric contract and the
response procedure for each alert. Register the new alert rules file in
the observability READMEs.
Refs rustfs/backlog#1584 (part of rustfs/backlog#1562)
Zhengchao An