Add changelog

Author: DZakh

CHANGELOG.md

@@ -15,6 +15,7 @@
 #### :rocket: New Feature
 
 - Allow coercing polyvariants to variants when we can guarantee that the runtime representation matches. https://github.com/rescript-lang/rescript-compiler/pull/6981
+- 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