Breaking changes mention added in release notes.

Author: yaroslavyaroslav

messages/4.0.0.md

@@ -18,6 +18,10 @@ Well, you know all of them:
 
 This is a really huge update. So is you're happy with it, this is the place and time to [donate me](https://github.com/sponsors/yaroslavyaroslav). 
 
+## Breaking changes
+
+`output.OpenAI Chat` renamed to `output.AI Chat`, please update your output panel binding to handle this change.
+
 ## Details
 
 ### Dedicated history and settings