Add documentation about configuring the app

README.md

@@ -5,6 +5,46 @@ Display bus departures for specific routes on specific stops.
 Usage:
 
 ```shell
-./busdepartures[ -p=PORT]
+./busdepartures -c=CONFIGFILE [ -p=PORT]
 ```
 
+## Configuration
+
+The configuration file describes the list of quays (or stops) and the routes for
+each quay that you're interested in. Each quay in your configuration should look
+something like this:
+
+```toml
+[[quays]]
+id = "NL:Q:40004001"
+name = "Centraal Station"
+town = "Arnhem"
+routes_of_interest = [
+    {"short_name" = "51", "long_name" = "Wageningen"},
+    {"short_name" = "352", "long_name" = "Wageningen"},
+]
+```
+
+Note that the `[[quay]]` syntax is TOML's way of describing a list, meaning you
+can keep repeating the example above in your configuration to add multiple
+quays. If you would like an example, see the `config.toml.example` file. It
+lists multiple quays.
+
+### Finding the information required for configuration
+
+1. Open [the Connexxion halte-informatie page](https://www.connexxion.nl/nl/resultaten/halte-informatie).
+2. Open your browser's developer tooling and go to the 'network' tab.
+3. Search for your stop on the website and open it.
+4. In the network tab, there should be a request labeled 'departures'. Open it.
+
+The response is in JSON format and contains all the information you need.
+
+- The quay ID is almost exactly the `stopid`, just replace the `:S:` with `:Q:`.
+- The `name` and `town` are just below the quay ID.
+- All the route information you'll need is available in the `departures` key.
+  - `departures.X.tripdata.route.route_short_name` is what you'll enter as the
+    `short_name`.
+  - `departures.stop_headsign` is what you'll enter as the `long_name`.
+
+And that's it. Add the information you found to your `config.toml`, as described
+above and start the application.