Generate documentation for all the packages.
pkg> add DocumentationGenerator
installs this package.
It also makes sense to have xvfb-run installed so packages that require a display
(e.g. Tk.jl) work fine.
Running ./run/makedocs.jl will generate the documentation for all packages installable on the
current Julia version in ./build. ./dist will contain the correct directory structure.
Executing ./run/generate_json.jl creates a packages_meta.json in ./build, which powers the
frontend in ./landingpage.