Add 2.7.10 release notes

Author: NickCraver

docs/ReleaseNotes.md

@@ -7,6 +7,9 @@ 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 unreleased changes yet!
+
+## 2.7.10
 
 - Fix [#2593](https://github.com/StackExchange/StackExchange.Redis/issues/2593): `EXPIRETIME` and `PEXPIRETIME` miscategorized as `PrimaryOnly` commands causing them to fail when issued against a read-only replica ([#2593 by slorello89](https://github.com/StackExchange/StackExchange.Redis/pull/2593))
 - Fix [#2591](https://github.com/StackExchange/StackExchange.Redis/issues/2591): Add `HELLO` to Sentinel connections so they can support RESP3 ([#2601 by NickCraver](https://github.com/StackExchange/StackExchange.Redis/pull/2601))