Update release notes for 2.8.31

Author: NickCraver

docs/ReleaseNotes.md

@@ -7,7 +7,12 @@ Current package versions:
 | [![StackExchange.Redis](https://img.shields.io/nuget/v/StackExchange.Redis.svg)](https://www.nuget.org/packages/StackExchange.Redis/) | [![StackExchange.Redis](https://img.shields.io/nuget/vpre/StackExchange.Redis.svg)](https://www.nuget.org/packages/StackExchange.Redis/) | [![StackExchange.Redis MyGet](https://img.shields.io/myget/stackoverflow/vpre/StackExchange.Redis.svg)](https://www.myget.org/feed/stackoverflow/package/nuget/StackExchange.Redis) |
 
 ## Unreleased
+No pending unreleased changes
+
+## 2.8.31
+
 - Fix: Respect `IReconnectRetryPolicy` timing in the case that a node that was present disconnects indefinitely ([#2853](https://github.com/StackExchange/StackExchange.Redis/pull/2853) & [#2856](https://github.com/StackExchange/StackExchange.Redis/pull/2856) by NickCraver)
+  - Special thanks to [sampdei](https://github.com/sampdei) tracking this down and working a fix
 - Changes max default retry policy backoff to 60 seconds ([#2853 by NickCraver](https://github.com/StackExchange/StackExchange.Redis/pull/2853))
 - Fix [#2652](https://github.com/StackExchange/StackExchange.Redis/issues/2652): Track client-initiated shutdown for any pipe type ([#2814 by bgrainger](https://github.com/StackExchange/StackExchange.Redis/pull/2814))