Update changelog for progress reporting on post-evaluation steps

Author: nickrolfe

extensions/ql-vscode/CHANGELOG.md

@@ -3,6 +3,7 @@
 ## [UNRELEASED]
 
 - Fix a bug when re-importing test databases that erroneously showed old source code. [#3616](https://github.com/github/vscode-codeql/pull/3616)
+- Update the progress window with details on potentially long-running post-processing steps after running a query. [#3622](https://github.com/github/vscode-codeql/pull/3622)
 
 ## 1.13.0 - 1 May 2024