add changelog

Author: cometkim

CHANGELOG.md

@@ -22,6 +22,10 @@
 
 - Stop escaping JSX prop names with hyphens. https://github.com/rescript-lang/rescript-compiler/pull/6705
 
+#### :nail_care: Polish
+
+- Module spec `es6` and `es6-global` is deprecated in favor of `esmodule`. https://github.com/rescript-lang/rescript-compiler/pull/6709
+
 # 11.1.0-rc.7
 
 #### :bug: Bug Fix