Update 3.12.0.md

Author: michaelklishin

release-notes/3.12.0.md

@@ -1,6 +1,6 @@
-## RabbitMQ 3.12.0-rc.4
+## RabbitMQ 3.12.0
 
-RabbitMQ `3.12.0-rc.4` is a candidate of a new feature release.
+RabbitMQ `3.12.0` is a new feature release.
 
 ## Highlights
 
@@ -42,10 +42,8 @@ what package repositories and tools can be used to provision latest patch versio
 
 ### Erlang 26
 
-Erlang 26 introduces a number of breaking changes around networking and TLS. At the moment,
-RabbitMQ should not be considered fully compatible with Erlang 26. Erlang 26 compatibility
-will be announced separately.
-
+This is the first release that offers Erlang 26 compatibility. Note that Erlang 26 is very new and
+is nowhere near as battle tested as Erlang 25.
 
 ## Upgrading to 3.12