Update CHANGELOG.md

Author: radeksimko

CHANGELOG.md

@@ -2,9 +2,14 @@
 
 ## v2.20.0 (unreleased)
 
+### Enhancements
+
+* Support for namespaced functions ([#639](https://github.com/hashicorp/hcl/pull/639))
+
 ### Bugs Fixed
 
-* ext/dynblock: if `iterator` is invalid return this error instead of consequential errors. ([#656](https://github.com/hashicorp/hcl/pull/656))
+* ext/dynblock: if `iterator` is invalid return this error instead of consequential errors ([#656](https://github.com/hashicorp/hcl/pull/656))
+* hclwrite: Fix formatting of namespaced functions ([#658](https://github.com/hashicorp/hcl/pull/658))
 
 ## v2.19.0 (October 16, 2023)