docs(telemetry): align runbook and plan docs with the shipped phase-9/10 code

The reference docs had drifted from the code in ways that break the reader
rather than merely misinform: PromQL examples that return no data, a rollback
flag that is a no-op, a sampling knob that does not exist, and two span parents
that moved. Code is treated as the truth throughout; where the code is the
defective side, the doc now records it as a known issue instead of describing
the bug as intent.

Renames the docs missed: histogram names gain the exporter's unit suffix
(ios_latency_milliseconds_bucket and four siblings), ledger_history_mismatch
gains _total, the StatsD-era quantile label gives way to le buckets,
rpc.request becomes rpc.http_request, traces_spanmetrics_calls_total becomes
span_calls_total, and the nine dotted xrpl.* span attributes are recorded as
renamed rather than left as live keys.

Re-parenting: consensus.update_positions and consensus.check are children of
consensus.establish, not of consensus.round.

Units and labels: state_accounting_*_duration is microseconds, not seconds;
cache_metrics label values are case-sensitive; object_count carries demangled
C++ type names. Nodestore read and write latency stays microseconds -- the
nanosecond accumulator change did not move the exported unit.

Adds what shipped but was undocumented: the ledger.acquire span, seven
consensus.round events, twelve span attributes, node_writes_duration_us, the
7-day validation-agreement window, the TxQ admission and reduce-relay metric
families, metrics_endpoint, and the phase-10 validation workflow.

Corrects claims that never held: 10% head sampling (it is fixed at 100%),
configurable redaction (it is unconditional), -DXRPL_ENABLE_TELEMETRY=OFF
(the flag is -Dtelemetry=OFF, default ON), FindOpenTelemetry.cmake and the
xrpl_telemetry target (neither exists), Promtail and a StatsD exporter in the
pipeline (neither exists), and Loki stream selection on job= (only
service_name is a stream label).

Phase 9 is marked complete, its provisioned alerting is attributed to the
branch that shipped it, and Phase 11 stays at zero except the one prerequisite
its code closes. Counts are reconciled repo-wide: 41 emitted span families,
15 dashboards on disk with 14 asserted, 13 alert rules in 5 groups.

Hardens the gate that let this drift through: Rule E of the naming check now
covers the reference docs, its allow-dotted marker is key-scoped and warns on
stale or empty use, a missing checked file is reported instead of silently
skipped, the test suite runs in CI, and doc paths trigger the check.

C++ and CMake changes are comment-only: three MetricsRegistry instrument names,
eight OTelCollector claims of a metric-name prefix that formatName never adds,
and the telemetry option's inverted default.

.github/workflows/on-pr.yml

@@ -77,6 +77,16 @@ jobs:
             .github/workflows/reusable-check-rename.yml
             .github/workflows/on-pr.yml
 
+            # The non-code layers the OTel naming check validates: the docs that
+            # publish attribute tables (Rule E) and the telemetry stack config —
+            # collector, Tempo, dashboards (Rules B, C, D). Without these paths a
+            # docs-only or dashboard-only pull request sets `go=false`, so the
+            # very layers those rules exist to police would never be checked.
+            # As with `README.md` below, matching one of these also switches on
+            # the rest of the workflow; there is a single `go` gate.
+            docs/**
+            docker/telemetry/**
+
             # Keep the paths below in sync with those in `on-trigger.yml`.
             .github/actions/build-deps/**
             .github/actions/generate-version/**

.github/workflows/reusable-check-otel-naming.yml

@@ -21,6 +21,13 @@ jobs:
     steps:
       - name: Checkout repository
         uses: actions/checkout@df4cb1c069e1874edd31b4311f1884172cec0e10 # v6.0.3
+      - name: Test the OTel naming checker
+        # The checker's own unit tests, run before the check itself so a broken
+        # rule is reported as a broken rule rather than as a naming violation
+        # (or, worse, as a rule that silently stops flagging anything).
+        # stdlib `unittest` only: the repo installs no third-party test runner
+        # for CI, and the checker itself is deliberately dependency-free.
+        run: python -m unittest discover -s .github/scripts/otel-naming -p 'test_*.py' --verbose
       - name: Check OTel naming
         # The script is stdlib-only and reads only files already in the tree;
         # it enforces each rule only when the layer it needs is present, so it