Update CHANGELOG.md (#432)

Author: mikemorris

CHANGELOG.md

@@ -3,6 +3,19 @@
 IMPROVEMENTS
 
 * Remove `StartAsLeader` configuration option [[GH-364](https://github.com/hashicorp/raft/pull/386)]
+* Allow futures to react to `Shutdown()` to prevent a deadlock with `takeSnapshot()` [[GH-390](https://github.com/hashicorp/raft/pull/390)]
+* Prevent non-voters from becoming eligible for leadership elections [[GH-398](https://github.com/hashicorp/raft/pull/398)]
+* Remove an unneeded `io.Copy` from snapshot writes [[GH-399](https://github.com/hashicorp/raft/pull/399)]
+* Log decoded candidate address in `duplicate requestVote` warning [[GH-400](https://github.com/hashicorp/raft/pull/400)]
+* Prevent starting a TCP transport when IP address is `nil` [[GH-403](https://github.com/hashicorp/raft/pull/403)]
+* Reject leadership transfer requests when in candidate state to prevent indefinite blocking while unable to elect a leader [[GH-413](https://github.com/hashicorp/raft/pull/413)]
+* Add labels for metric metadata to reduce cardinality of metric names [[GH-409](https://github.com/hashicorp/raft/pull/409)]
+* Add peers metric [[GH-413](https://github.com/hashicorp/raft/pull/431)]
+
+BUG FIXES
+
+* Make `LeaderCh` always deliver the latest leadership transition [[GH-384](https://github.com/hashicorp/raft/pull/384)]
+* Handle updating an existing peer in `startStopReplication` [[GH-419](https://github.com/hashicorp/raft/pull/419)]
 
 # 1.1.2 (January 17th, 2020)