Update CHANGELOG.md

Author: cristianoc

CHANGELOG.md

@@ -21,6 +21,7 @@
 subset of the arguments, and return a curried type with the remaining ones https://github.com/rescript-lang/rescript-compiler/pull/5805
 - Add support for uncurried externals https://github.com/rescript-lang/rescript-compiler/pull/5815 https://github.com/rescript-lang/rescript-compiler/pull/5819 https://github.com/rescript-lang/rescript-compiler/pull/5830
 - Parser/Printer: unify uncurried functions of arity 0, and of arity 1 taking unit. There's now only arity 1 in the source language. https://github.com/rescript-lang/rescript-compiler/pull/5825
+- Add support for default arguments in uncurried functions https://github.com/rescript-lang/rescript-compiler/pull/5835
 
 
 #### :boom: Breaking Change