Update docs

docs/getting-started.md

@@ -27,6 +27,22 @@ These **optional** values are defined in your `mopidy.conf` file (typically `~/.
 - `spotify_authorization_url` URL to use as Spotify authentication proxy (defaults to `https://jamesbarnsley.co.nz/auth_spotify.php`)
 - `lastfm_authorization_url ` URL to use as LastFM authentication proxy (defaults to `https://jamesbarnsley.co.nz/auth_lastfm.php`)
 
+### User Configuration
+
+Each user which connects to Iris has their own settings, stored in `localStorage`. You can use the `Application` inspector in Developer Tools to view this data, or type `_store.getState()` in the console. To share settings between users, you can use `Share configuration` button in **Settings -> Advanced**.
+
+### Bypassing Login
+
+To bypass the login, you can use query params to assign JSON values directly to the User Configuration (see prior section for help determining appropriate values).
+
+Examples:
+
+* Skip the `initial-setup` screen: `/iris/?ui={"initial_setup_complete":true}`
+* Set the username: `/iris?pusher={"username": "hello"}`
+* Enable `snapcast`: `/iris/?snapcast={"enabled":true,"host":"my-host.com","port":"443"}`
+
+This may alse be used to enable Spotify, by passing `?spotify={...}` with the valid token data. However, please be aware that this entails sharing a single login between sessions. Anybody with the pre-configured URL will be able to use the Spotify account in Iris. If the original user (who created the Spotify session) logs out, the token will **continue to work** for other users who access the page (the logout action does not invalidate the token for other users).
+
 ## Upgrading
 You can upgrade from Iris under _Settings_ > _Upgrade_. This is in beta, and you will need to restart Mopidy for the upgrade to complete. Alternatively run `sudo pip install --upgrade Mopidy-Iris`.