-There are lots of configuration settings you can tweak. Have a look
-at `settings/default.php` for a full list. Most should have a sensible default.
+### Configuration setup in `.env`
+
+The Nominatim server can be customized via an `.env` configuration file in the
+project directory. This is a file in [dotenv](https://github.com/theskumar/python-dotenv)
+format which looks the same as variable settings in a standard shell environment.
+You can also set the same configuration via environment variables. All
+settings have a `NOMINATIM_` prefix to avoid conflicts with other environment
+variables.
+
+There are lots of configuration settings you can tweak. A full reference
+can be found in the chapter [Configuration Settings](../customize/Settings.md).
+Most should have a sensible default.