How to change output extension from html -> php

1

Hi.
I tried this, but without success.

 "mediaTypes": {
    "text/html": {
       "suffixes": ["php"]
    }
 },
 "outputFormats": {
    "HTML": {
        "mediaType": "text/html"
    }
 }

The documentation seems to be out of date

2

Which part?

3

converrting my config to json

  "mediaTypes": {
    "application/atom+xml": {
      "suffixes": ["xml"]
    }
  },
  "outputFormats": {
    "ATOM": {
      "MediaType": "application/atom+xml",
      "BaseName": "feed",
      "Rel": "alternate"
    }
  }

difference on the first look, only some letters in uppercase