It looks like documentation references to `ring-router` are left-overs
from early README examples - I couldn't find any code that ever used the
name. The Ring router named `reitit.ring/router`.
While it didn't take too long for me to realize why my `ring-router` was
not working, I had to look the examples to figure out the name of the
function was just `router` - which was confusing since the section
header stated `reitit-router`.