Update readme

README.md

@@ -9,7 +9,7 @@ alphanumeric strings like "/1Cqw8lHw" used by several services.
 
 It was inspired by [hastebin](http://hastebin.com).
 
-## Installing the app
+## Installing
 
 Install the app with cabal-install. Run
 
@@ -21,7 +21,21 @@ and start it with
 
 The app will start serving on `http://localhost:3000`, listening on every active interface.
 
-You can change the port and set a hostname via the `PORT` and `HOSTNAME` environment variables.
+## Configure
+
+You can change the options by editing the config file.
+When you start the app an empty one will be created in:
+`$XDG_CONFIG_HOME/breve` or `~/.config/breve` if unset.
+
+The default values are:
+
+```ini
+hostname localhost
+port     3000
+urltable $XDG_CONFIG_HOME/breve
+```
+
+`urltable` is the location of breve url hashtable
 
 ## License