Locks the railroad diagrams to always use the same font, this one named
`roboto mono`. This makes sure that when we render the railroad diagrams
we always size them the same way. Because everyone has a copy of roboto
mono. Because gradle resolves that dependency.
This generates a "railroad diagram" svg image that can be embedded into
the docs for any function to explain it's syntax. It's basic, but it's
something we can iterate on.
It also generates a table of supported types from the list of types that
we test. It can be included in the docs for reference as well.
