Update CHANGELOG.md

Author: cristianoc

CHANGELOG.md

@@ -47,6 +47,7 @@
 - Convert OCaml codebase to snake case style. https://github.com/rescript-lang/rescript-compiler/pull/6702
 - Fix location of let bindings with attributes. https://github.com/rescript-lang/rescript-compiler/pull/6791
 - Refactor uppercase exotic ident handling. https://github.com/rescript-lang/rescript-compiler/pull/6779
+- Remove a number of ast nodes never populated by the .res parser, and resulting dead code. https://github.com/rescript-lang/rescript-compiler/pull/6830
 
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