Update state when document generatorSettings change

I'm updating the auto-generate setting programmatically and just setting the menu item with JSX wasn't triggering the StateManager to update. Instead I'm updating the document setting and then the StateManager can pickup that change and manage the menu item the same way it normally does.
Nit: this should be `.done` instead of `.then` because the responsibility for handling any error ends here. Alternatively, you can add a `.fail` handler after the `.then` handler and log the error.