Merge pull request #9849 from wenjiaswe/changelog49848

CHANGELOG-3.1: update from #9848

CHANGELOG-3.1.md

@@ -2,6 +2,14 @@
 
 Previous change logs can be found at [CHANGELOG-3.0](https://github.com/coreos/etcd/blob/master/CHANGELOG-3.0.md).
 
+## [v3.1.18](https://github.com/coreos/etcd/releases/tag/v3.1.18) (TBD 2018-06)
+
+See [code changes](https://github.com/coreos/etcd/compare/v3.1.17...v3.1.18) and [v3.1 upgrade guide](https://github.com/coreos/etcd/blob/master/Documentation/upgrades/upgrade_3_1.md) for any breaking changes. **Again, before running upgrades from any previous release, please make sure to read change logs below and [v3.1 upgrade guide](https://github.com/coreos/etcd/blob/master/Documentation/upgrades/upgrade_3_1.md).**
+
+### Metrics, Monitoring
+
+- Add [`etcd_server_version`](https://github.com/coreos/etcd/pull/8960) Prometheus metric.
+  - To replace [Kubernetes `etcd-version-monitor`](https://github.com/coreos/etcd/issues/8948).
 
 ## [v3.1.17](https://github.com/coreos/etcd/releases/tag/v3.1.17) (2018-06-06)