Update documentation to match the removal of `USE_SUBDOMAIN_EXCEPTION`.
Update documentation to match the removal of `USE_SUBDOMAIN_EXCEPTION`.

ipsosante/django-subdomains,adi-li/django-subdomains,jangeador/django-subdomains,tkaemming/django-subdomains,larikov/django-subdomains,messense/djsubdomains,aajtodd/django-subdomains,mysociety/django-subdomains,nanopony/django-subdomains