Remove recommendation to use a file extension to indicate format

[konklone]

I suggest we remove all use of the file extension (.json) to indicate the format of an API endpoint. This was fashionable for some time in the late 2000's -- especially for APIs that support multiple output formats -- but mime types in HTTP headers handle this far better. Plus, they communicate more information, like UTF-8 encoding.

[mlissner]

+1

[delfuego]

Didn't commit db3a2cb already do this?

[konklone]

Good catch!