Update changelog

Author: shulhi

CHANGELOG.md

@@ -32,6 +32,7 @@
 - Experimental support of tagged template literals, e.g. ```sql`select * from ${table}```. https://github.com/rescript-lang/rescript-compiler/pull/6250
 - Experimental support for generic/custom JSX transforms. https://github.com/rescript-lang/rescript-compiler/pull/6565
 - `dict` is now a builtin type. https://github.com/rescript-lang/rescript-compiler/pull/6590
+- Add support for array spread. https://github.com/rescript-lang/rescript-compiler/pull/6608
 
 #### :bug: Bug Fix