Replace link to Requests documentation (#3125)

Author: nateprewitt

README.md

@@ -166,8 +166,8 @@ Twisted and CPython:
 
 > At least the name is good.
 
-**Kenneth Reitz**, creator of [`requests`](http://python-requests.org/) and
-[`pipenv`](https://readthedocs.org/projects/pipenv/):
+**Kenneth Reitz**, creator of [`requests`](https://requests.readthedocs.io/en/latest/)
+and [`pipenv`](https://readthedocs.org/projects/pipenv/):
 
 > This vastly improves the formatting of our code. Thanks a ton!