Adding 2.8.12 release notes

Author: NickCraver

docs/ReleaseNotes.md

@@ -8,6 +8,10 @@ Current package versions:
 
 ## Unreleased
 
+No pending unreleased changes.
+
+## 2.8.12
+
 - Add support for hash field expiration (see [#2715](https://github.com/StackExchange/StackExchange.Redis/issues/2715)) ([#2716 by atakavci](https://github.com/StackExchange/StackExchange.Redis/pull/2716]))
 - Add support for `HSCAN NOVALUES` (see [#2721](https://github.com/StackExchange/StackExchange.Redis/issues/2721)) ([#2722 by atakavci](https://github.com/StackExchange/StackExchange.Redis/pull/2722))
 - Fix [#2763](https://github.com/StackExchange/StackExchange.Redis/issues/2763): Make ConnectionMultiplexer.Subscription thread-safe ([#2769 by Chuck-EP](https://github.com/StackExchange/StackExchange.Redis/pull/2769))