Update AppleMusicSourceManager example (#47)

* Update AppleMusicSourceManager example

Updated example to reflect current constructor, which includes a media API token

* Update README.md

Co-authored-by: ToπSenpai <git@topi.wtf>

README.md

@@ -70,8 +70,8 @@ playerManager.registerSourceManager(new SpotifySourceManager(null, clientId, cli
 ```java
 AudioPlayerManager playerManager = new DefaultAudioPlayerManager();
 
-// create a new AppleMusicSourceManager with the standard providers, countrycode and AudioPlayerManager and register it
-playerManager.registerSourceManager(new AppleMusicSourceManager(null, "us", playerManager));
+// create a new AppleMusicSourceManager with the standard providers, token(pass null for automatic extraction), countrycode and AudioPlayerManager and register it
+playerManager.registerSourceManager(new AppleMusicSourceManager(null, mediaAPIToken , "us", playerManager));
 ```
 
 #### Deezer