remove obsolete file

website/documentation/content/more/shutdown_documentation.py

@@ -1,12 +0,0 @@
-from nicegui import ui
-
-
-def main_demo() -> None:
-    from nicegui import app
-
-    # ui.button('shutdown', on_click=app.shutdown)
-    #
-    # ui.run(reload=False)
-    # END OF DEMO
-    ui.button('shutdown', on_click=lambda: ui.notify(
-        'Nah. We do not actually shutdown the documentation server. Try it in your own app!'))