Update installation.rst
Update installation.rst

Add urlpatterns for django version 2.0 or later
jazzband/django-debug-toolbar,django-debug-toolbar/django-debug-toolbar,tim-schilling/django-debug-toolbar,spookylukey/django-debug-toolbar,tim-schilling/django-debug-toolbar,django-debug-toolbar/django-debug-toolbar,django-debug-toolbar/django-debug-toolbar,jazzband/django-debug-toolbar,spookylukey/django-debug-toolbar,tim-schilling/django-debug-toolbar,jazzband/django-debug-toolbar,spookylukey/django-debug-toolbar