Merge pull request #914 from estan/fix-developer-guide-link

Fix broken link in docs/developer-guide.txt

docs/developer-guide.txt

@@ -13,11 +13,11 @@ Recommended Reading
 -------------------
 
 Please read `How to write the perfect pull request
-<http://blog.jaraco.com/2014/04/how-to-write-perfect-pull-request.html>`_
-for some tips on contributing to open source projects. Although the article
-is not authoritative, it was authored by the maintainer of Setuptools, so
-reflects his opinions and will improve the likelihood of acceptance and
-quality of contribution.
+<https://blog.jaraco.com/how-to-write-perfect-pull-request/>`_ for some tips
+on contributing to open source projects. Although the article is not
+authoritative, it was authored by the maintainer of Setuptools, so reflects
+his opinions and will improve the likelihood of acceptance and quality of
+contribution.
 
 ------------------
 Project Management