Update settings.rst
Update settings.rst

Adds 'unauthenticated_user' setting
marcgibbons/django-rest-swagger,cancan101/django-rest-swagger,sacgup/django-rest-swagger,pombredanne/django-rest-swagger,visasq/django-rest-swagger,sacgup/django-rest-swagger,arc6373/django-rest-swagger,pombredanne/django-rest-swagger,marcgibbons/django-rest-swagger,arc6373/django-rest-swagger,marcgibbons/django-rest-swagger,aioTV/django-rest-swagger,pombredanne/django-rest-swagger,aioTV/django-rest-swagger,visasq/django-rest-swagger,marcgibbons/django-rest-swagger,pombredanne/django-rest-swagger,cancan101/django-rest-swagger,cancan101/django-rest-swagger,arc6373/django-rest-swagger,visasq/django-rest-swagger,sacgup/django-rest-swagger,aioTV/django-rest-swagger