Update signals.rst
Update signals.rst

Added missing request parameter
bittner/django-allauth,bittner/django-allauth,rsalmaso/django-allauth,pennersr/django-allauth,lukeburden/django-allauth,lukeburden/django-allauth,lukeburden/django-allauth,rsalmaso/django-allauth,pennersr/django-allauth,AltSchool/django-allauth,bittner/django-allauth,pztrick/django-allauth,AltSchool/django-allauth,rsalmaso/django-allauth,pztrick/django-allauth,pennersr/django-allauth,pztrick/django-allauth,AltSchool/django-allauth