Add changelog

Author: DZakh

CHANGELOG.md

@@ -12,6 +12,10 @@
 
 # 12.0.0-alpha.2 (Unreleased)
 
+#### :rocket: New Feature
+
+- Use `RescriptError` for runtime representation of exceptions and fix regression with not being able to throw raw Js values. https://github.com/rescript-lang/rescript-compiler/pull/6979
+
 #### :nail_care: Polish
 
 - Improve formatting in the generated js code. https://github.com/rescript-lang/rescript-compiler/pull/6932