Update README.rst

Author: Mohammed Hammoud

README.rst

@@ -10,7 +10,8 @@ Django REST Framework wrapper of the payments Django app for Stripe
 Install
 ======================
 * pip install django-rest-framework-stripe
-* **Add to urls.py:** ``url(r"^api/stripe/", include("django_rest_framework_stripe.payments.api.urls")),``
+* Add 'payments' to INSTALLED_APPS
+* **Add to urls.py:** ``url(r"^api/stripe/", include("payments.api.urls"))``
 
 Endpoints
 ======================