Update README

Add information about migrate and admin right on local dev

README.md

@@ -28,5 +28,15 @@ DEBUG = True
 SECRET_KEY = 'what you want'
 ```
 
-When you'll run `python manage.py runserver`, an empty database will be automatically created.  
+When you'll run `python manage.py migrate` then `python manage.py runserver`, an empty database will be automatically created.  
 The `local_settings.py` is in the `.gitignore` and should stay that way, so we don't accidentally overwrite the production file when we deploy.
+
+To obtain administrator rights you must create a user on the platform. Then you can run `python manage.py shell` and type the following commands:
+```
+from django.contrib.auth.models import User
+user = User.objects.get(username="<your_username>")
+user.is_staff = True
+user.is_admin = True
+user.is_superuser = True
+user.save()
+```