Minor fix on doc.
Minor fix on doc.

rodo/django-pgjson,moradology/django-pgjson,mamigot/django-pgjson,djangonauts/django-pgjson,moradology/django-pgjson,mamigot/django-pgjson,uditagarwal/django-pgjson,djangonauts/django-pgjson,rodo/django-pgjson,uditagarwal/django-pgjson