Update CHANGELOG.md

add AST exploration tool link

Co-authored-by: Bastian Müller <[email protected]>

CHANGELOG.md

@@ -1099,9 +1099,7 @@ For `AuthAccount`:
   - `monaco-languageclient-cadence`: Language Server Protocol client for the the Monaco editor
   - `cadence-parser`: The Cadence parser
 
-  In addition, there is also an example for the [language server](https://github.com/onflow/cadence/tree/master/npm-packages/cadence-language-server-demo) 
-  <!-- and the [parser](https://github.com/onflow/cadence/tree/master/npm-packages/cadence-parser-demo) that demonstrate the use of the packages.
-  >>
+  In addition, there is also [an example for the language server](https://github.com/onflow/cadence/tree/master/npm-packages/cadence-language-server-demo), and an [AST exploration tool](https://github.com/onflow/cadence/tree/master/tools/astexplorer) that demonstrate the use of the parser package.
 
 - Add a command to the language server that allows getting the entry point (transaction or script) parameters (#406)