add login warning for application registration to docs (#713)

Author: ermissa

docs/tutorial/tutorial_01.rst

@@ -85,7 +85,8 @@ the API, subject to approval by its users.
 
 Let's register your application.
 
-Point your browser to http://localhost:8000/o/applications/ and add an Application instance.
+You need to be logged in before registration. So, go to http://localhost:8000/admin and log in. After that 
+point your browser to http://localhost:8000/o/applications/ and add an Application instance.
 `Client id` and `Client Secret` are automatically generated; you have to provide the rest of the informations:
 
  * `User`: the owner of the Application (e.g. a developer, or the currently logged in user.)