update CHANGELOG.md

Author: aspeddro

Diff for: CHANGELOG.md

@@ -16,6 +16,10 @@
 
 - Add support for syntax highlighting in `%raw` and `%ffi` extension points. https://github.com/rescript-lang/rescript-vscode/pull/774
 
+#### :bug: Bug Fix
+
+- Fix invalid range for `definition`. https://github.com/rescript-lang/rescript-vscode/pull/781
+
 ## 1.18.0
 
 #### :rocket: New Feature