Document adding django_filters to installed apps
Document adding django_filters to installed apps

Reminds users to add `django_filters` to their `INSTALLED_APPS` as detailed in the django-filter documentation https://django-filter.readthedocs.io/en/develop/guide/install.html
atombrella/django-rest-framework,ossanna16/django-rest-framework,davesque/django-rest-framework,jpadilla/django-rest-framework,kgeorgy/django-rest-framework,jpadilla/django-rest-framework,linovia/django-rest-framework,tomchristie/django-rest-framework,tomchristie/django-rest-framework,edx/django-rest-framework,edx/django-rest-framework,davesque/django-rest-framework,atombrella/django-rest-framework,davesque/django-rest-framework,atombrella/django-rest-framework,tomchristie/django-rest-framework,jpadilla/django-rest-framework,dmwyatt/django-rest-framework,linovia/django-rest-framework,edx/django-rest-framework,ossanna16/django-rest-framework,linovia/django-rest-framework,dmwyatt/django-rest-framework,dmwyatt/django-rest-framework,ossanna16/django-rest-framework,kgeorgy/django-rest-framework,kgeorgy/django-rest-framework