Update changelog

Author: aeisenberg

extensions/ql-vscode/CHANGELOG.md

@@ -5,6 +5,7 @@
 - Better formatting and autoindentation when adding QLDoc comments to `.ql` and `.qll` files.
 - Allow for more flexibility when opening a database in the workspace. A user can now choose the actual database folder, or the nested `db-*` folder.
 - Add query history menu command for viewing corresponding SARIF file.
+- Add ability for users to download databases directly from LGTM.com.
 
 ## 1.2.0 - 19 May 2020