Fixed database update instructions

Author: LuRsT

docs/tutorial/4-authentication-and-permissions.md

@@ -44,7 +44,9 @@ When that's all done we'll need to update our database tables.
 Normally we'd create a database migration in order to do that, but for the purposes of this tutorial, let's just delete the database and start again.
 
     rm tmp.db
-    python manage.py syncdb
+    rm -r snippets/migrations
+    python manage.py makemigrations snippets
+    python manage.py migrate
 
 You might also want to create a few different users, to use for testing the API.  The quickest way to do this will be with the `createsuperuser` command.