Add heading levels to the PDF export of a reading list

The PDF export of a reading list does not contain heading levels which would enable screen reader users to navigate to different sections using quick navigation keys. This makes it extremely time-consuming to try locate or access the readings for any particular topic module.

Due to the inability to reliably navigate a reading list online it is necessary to work from a downloaded document, but currently this option does not remove the accessibility barrier. This issue has persisted for a number of years, and a resolution would be much appreciated. Once students fall behind it's near impossible to catch up, and this is an easy fix.