ref-docs: security: add certificate rotation timestamp and expiry days metrics

src/current/v26.1/cli.md

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+---
+title: security: add certificate rotation timestamp and expiry days metrics
+summary: I need to clarify something important about this request.
+toc: true
+docs_area: reference.cli
+---
+
+I need to clarify something important about this request. 
+
+**PR #167902 does not introduce any new CLI commands.** The "Extracted Commands" section confirms this: "(No CLI commands detected in diff)".
+
+Instead, this PR introduces **new certificate lifecycle metrics** that would be documented in the monitoring/metrics section of the reference documentation, not the CLI commands section.
+
+The PR adds two families of metrics:
+
+1. **`security.certificate.last_rotation.*`** - Unix timestamps of last certificate rotations
+2. **`security.certificate.expiry_days.*`** - Days until certificate expiration
+
+These metrics would be exposed through existing monitoring endpoints (like `/metrics` or queried via `crdb_internal.node_metrics`), not through new CLI commands.
+
+Would you like me to:
+
+1. **Generate metrics reference documentation** for these new certificate lifecycle metrics instead?
+2. **Generate supplementary monitoring guidance** showing how to query and alert on these metrics?
+3. **Clarify what specific documentation type you need** for this PR?
+
+The appropriate documentation for this PR would be metrics reference content, not CLI command documentation.