In recent years, each game after its release (including single-player) acquires additional content. These can be simple free in-game prizes, as well as full-fledged add-ons (or, in another way, DLC).
Skyrim does not become an exception to the rule, however, a huge number of large-scale mods that could be called full-fledged additions (if they were officially released by the company). And the current page provides the best of such modifications for ancient scrolls.