Add license from Spotify

src/server.js

@@ -4,11 +4,15 @@
  */
 
 /**
- * This is an example of a basic node.js script that performs
+ * The functions tagged as "From Spotify tutorial"
+ * are from an example of a basic node.js script that performs
  * the Authorization Code oAuth2 flow to authenticate against
  * the Spotify Accounts.
  *
- * For more information, read
+ * It's licensed under Apache 2.0.
+ * See https://github.com/spotify/web-api-auth-examples for more information.
+ *
+ * For more information about the tutorial, read
  * https://developer.spotify.com/web-api/authorization-guide/#authorization_code_flow
  */
 
@@ -60,6 +64,7 @@ app.get('/login', function (req, res) {
     res.cookie(stateKey, state);
 
     // your application requests authorization
+    // Changed scopes from Spotify tytorial
     var scope = 'playlist-read-private playlist-read-collaborative';
     res.redirect('https://accounts.spotify.com/authorize?' +
         querystring.stringify({