add CHANGELOG

Author: cometkim

CHANGELOG.md

@@ -185,6 +185,10 @@ No changes compared to rc.9.
 - Improve `rescript` CLI to use `stdout`/`stderr` appropriately for help command's message. https://github.com/rescript-lang/rescript-compiler/pull/6439
 - Generate `f()` instead of `f(undefined)` for `f()`. https://github.com/rescript-lang/rescript-compiler/pull/6459
 
+#### :boom: Breaking Change
+
+- Drop Node.js v16 support, due to it reaching End-of-Life. https://github.com/rescript-lang/rescript-compiler/pull/6429
+
 # 11.0.0-rc.4
 
 #### :rocket: New Feature