EDITED:
I added this to a plugin functions.php file:
add_filter( ‘generate_post_date_show_updated_only’, ‘__return_true’ );
I then I added “Last Updated” prefix using .updated-date:before {…}
(The number of times this specific question was asked/answered suggests it might be time to add this feature as a GUI-able option to the Theme instead of resorting to CSS and filters). But my question now is: what’s the easy way to adjust the spacing below the date line on posts (not pages)?
Thanks