Fix Links in Documentation to Django reverse and reverse_lazy (encode#8986)

* Fix Django Docs url in reverse.md

Django URLs of the documentation of `reverse` and `reverse_lazy` were wrong.

* Update reverse.md

Author: theomega

docs/api-guide/reverse.md

@@ -54,5 +54,5 @@ As with the `reverse` function, you should **include the request as a keyword ar
     api_root = reverse_lazy('api-root', request=request)
 
 [cite]: https://www.ics.uci.edu/~fielding/pubs/dissertation/rest_arch_style.htm#sec_5_1_5
-[reverse]: https://docs.djangoproject.com/en/stable/topics/http/urls/#reverse
-[reverse-lazy]: https://docs.djangoproject.com/en/stable/topics/http/urls/#reverse-lazy
+[reverse]: https://docs.djangoproject.com/en/stable/ref/urlresolvers/#reverse
+[reverse-lazy]: https://docs.djangoproject.com/en/stable/ref/urlresolvers/#reverse-lazy