Fix typo in example (#106)

Author: abdelwahebmoalla

README.md

@@ -35,7 +35,7 @@ from apns2.credentials import TokenCredentials
 auth_key_path = 'path/to/auth_key'
 auth_key_id = 'app_auth_key_id'
 team_id = 'app_team_id'
-token_credentials = TokensCredentials(auth_key_path=auth_key_path, auth_key_id=auth_key_id, team_id=team_id)
+token_credentials = TokenCredentials(auth_key_path=auth_key_path, auth_key_id=auth_key_id, team_id=team_id)
 client = APNsClient(credentials=token_credentials, use_sandbox=False)
 client.send_notification_batch(notifications=notifications, topic=topic)
 ```
@@ -82,4 +82,4 @@ PyAPNs2 is distributed under the terms of the MIT license.
 
 See [LICENSE](LICENSE) file for the complete license details.
 
-[a1]:https://developer.apple.com/library/content/documentation/NetworkingInternet/Conceptual/RemoteNotificationsPG/
+[a1]:https://developer.apple.com/documentation/usernotifications?language=objc