Update release notes (1.8.12)

RELEASENOTES.md

@@ -1,3 +1,14 @@
+# 1.8.12
+
+In this release, the `ChannelFactory` has been rewritten from the ground up. The old channel factory is left intact, but called `ThreadBasedChannelFactory`. One of the sync methods in the `IChannelFactory` interface is removed. It is recommended to use the async methods. All operations now use the new `ITopologyProvider` for creating topology features.
+
+ - [#66](https://github.com/pardahlman/RawRabbit/issues/66) - Upgrade to RabbitMQ.Client 3.6.1
+ - [#64](https://github.com/pardahlman/RawRabbit/issues/64) - Refactor Operations: Requester, Responder & Subscriber
+ - [#59](https://github.com/pardahlman/RawRabbit/issues/59) - vNext & default ChannelFactory
+
+Commits: bfa88b3083...3e7626fd0d
+
+
 # 1.8.11
 
  - [#61](https://github.com/pardahlman/RawRabbit/issues/61) - Improve extraction of Application Name (contributed by ([Originalutter](https://github.com/Originalutter)))