docs: Add Copilot limitations related to offline work (#4695)

Co-authored-by: Tatu Lund <[email protected]>

Author: MarcinVaadin

articles/tools/copilot/index.adoc

@@ -324,6 +324,8 @@ It's best to know the limitations of software that you use. These are some known
 - Not all views or hierarchies can be edited via drag-and-drop. In particular, parts of the UI created programmatically (e.g., loops) can cause problems.
 - AI makes mistakes.
 - AI is currently limited to smaller one-view tasks.
+- Code manipulation features do not work with Vaadin offline license.
+- Requires Internet connection to provide AI features and validate license.
 
 === Additional Notes