Feature Request: Change urls with .json extension to application/json content type

[AndrewLeedham]

It would be nice if in addition to mapping similiar content-types to just application/json, if this plugin could also map urls e.g. https://www.rest.com/example.json that are served using say text/plain to application/json as well.

Similiar to what https://github.com/samlh/display-inline does for other extensions like .pdf etc.