CHANGELOG: update to add new metrics

CHANGELOG-3.2.md

@@ -27,6 +27,8 @@ See [List of metrics](https://github.com/etcd-io/etcd/tree/master/Documentation/
 Note that any `etcd_debugging_*` metrics are experimental and subject to change.
 
 - Fix bug where [db_compaction_total_duration_milliseconds metric incorrectly measured duration as 0](https://github.com/etcd-io/etcd/pull/10646).
+- Add [`etcd_debugging_mvcc_current_revision`](https://github.com/etcd-io/etcd/pull/11126) Prometheus metric.
+- Add [`etcd_debugging_mvcc_compact_revision`](https://github.com/etcd-io/etcd/pull/11126) Prometheus metric.
 
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CHANGELOG-3.3.md

@@ -23,6 +23,15 @@ See [code changes](https://github.com/etcd-io/etcd/compare/v3.3.15...v3.3.16) an
 
 - Compile with [*Go 1.12.9*](https://golang.org/doc/devel/release.html#go1.12) including [*Go 1.12.8*](https://groups.google.com/d/msg/golang-announce/65QixT3tcmg/DrFiG6vvCwAJ) security fixes.
 
+### Metrics, Monitoring
+
+See [List of metrics](https://github.com/etcd-io/etcd/tree/master/Documentation/metrics) for all metrics per release.
+
+Note that any `etcd_debugging_*` metrics are experimental and subject to change.
+
+- Add [`etcd_debugging_mvcc_current_revision`](https://github.com/etcd-io/etcd/pull/11126) Prometheus metric.
+- Add [`etcd_debugging_mvcc_compact_revision`](https://github.com/etcd-io/etcd/pull/11126) Prometheus metric.
+
 
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