Update modernandfree.js

Added new pageModule... module...
- This lets me set CSS classes from inside Notion. So hopefully this can lead to a more streamlined page loader, more modules (such as full-width gallery slideshows), and a standardized framework for myself!
- The biggest part of this is being able to add a class name in notion (using !${"type": "menunav"}) and it applies it to the host object AND to the body. This means I can now, for example, affect the main navbar if the page has a secondary navbar.