This is excellent, and as hit said it was missing.
I suppose you will tweak things as they go along as it's very very early days.
Would be good if there is a lossless screenshot format, and also maybe consider in the browsing 1 link per app (or per major revision to app), and then after that display all the different versions (either by another link page, or by a large expandable single page). I noticed there were so many versions of AMOS
The versions of a particular app(game) is something that is not provided by HOL apart from maybe a brief comment in the Notes section.