This page describes the various steps that Nixery goes through when
"procuring" an image.
The intention is to give users some more visibility into what is going
on and to make it clear that this is not just an image storage
service.
Executes the previously added mdBook on the previously added book
source to yield a directory that can be served by Nixery on its index
page.
This is one of those 'I <3 Nix' things due to how easy it is to do.
Uses mdBook[1] to generate a documentation overview page instead of
the previous HTML site.
This makes it possible to add more elaborate documentation without
having to deal with finicky markup.
[1]: https://github.com/rust-lang-nursery/mdBook
