GitLab

Note, terrible hack, I duplicated the list so that I could put it
last in Apt. Need to revisit later and make it more elegant

Add some more screenshots for Apt, keeping up with a bunch that I added
for CloudLab last week

Make all #:tags somewhat consistent

Always use @seclink instead of @secref. The latter is neat, but it's
just too hard to keep track of what the titles are.

Make all @seclinks resolve (in some cases creating stub sections)

Turns out that setting it in the top-level is not enough, so
move it to defs.rkt and use it in ever section