back/configuration: add /config.ini HTTP endpoint

back/configuration.en.md

@@ -2,6 +2,8 @@
 
 This document describes the ServNest configuration directives that are part of `config.ini` (distributed as `config.template.ini`). It's an INI file, parsed by [PHP's `parse_ini_file` function](https://www.php.net/manual/function.parse-ini-file.php). Every directive is expected to be present.
 
+This file is automatically published using HTTP as `/config.ini`.
+
 ## `[common]`
 
 ### `public_domains[]`