1421 missing import in documentation (#1424)

* docs: add missing import

* add name in authors

Author: giovanniacg

AUTHORS

@@ -56,6 +56,7 @@ Florian Demmer
 Frederico Vieira
 Gaël Utard
 Glauco Junior
+Giovanni Giampauli
 Hasan Ramezani
 Hiroki Kiyohara
 Hossein Shakiba

docs/tutorial/tutorial_05.rst

@@ -65,6 +65,7 @@ Now add a new file to your app to add Celery: :file:`tutorial/celery.py`:
     import os
 
     from celery import Celery
+    from django.conf import settings
 
     # Set the default Django settings module for the 'celery' program.
     os.environ.setdefault('DJANGO_SETTINGS_MODULE', 'tutorial.settings')