For setting cache-control headers (i.e. long max-age or immutable), overriding content-type that is normally detected from the filename.
In other words, explicit control over the headers returned.
(only if you know the file at this path will never change)
/fonts/* Cache-Control: public, max-age=365000000, immutable
(because by default Roast will return application/octet-stream for files without extension)
/apple-app-site-association content-type: application/json