CHANGELOG: prepare for v2.19.0 release

CHANGELOG.md

@@ -1,5 +1,15 @@
 # HCL Changelog
 
+## v2.19.0 (October 16, 2023)
+
+### Enhancements
+
+* ext/dynblock: `dynblock.Expand` now supports an optional hook for calling applications to check and potentially veto (by returning error diagnostics) particular `for_each` values. The behavior is unchanged for callers that don't set the new option. ([#634](https://github.com/hashicorp/hcl/pull/634))
+
+### Bugs Fixed
+
+* hclsyntax: Further fixes for treatment of "marked" values in the conditional expression, and better tracking of refined values into the conditional expression results, building on the fixes from v2.18.1. ([#633](https://github.com/hashicorp/hcl/pull/633))
+
 ## v2.18.1 (October 5, 2023)
 
 ### Bugs Fixed