Fixed links to sphinx docs (#4182)
diff --git a/docs/development/submitting-patches.rst b/docs/development/submitting-patches.rst
index 431673e..2e9bb0f 100644
--- a/docs/development/submitting-patches.rst
+++ b/docs/development/submitting-patches.rst
@@ -155,7 +155,7 @@
.. _`Write comments as complete sentences.`: https://nedbatchelder.com/blog/201401/comments_should_be_sentences.html
-.. _`syntax`: http://sphinx-doc.org/domains.html#info-field-lists
+.. _`syntax`: http://www.sphinx-doc.org/en/master/usage/restructuredtext/domains.html#info-field-lists
.. _`Studies have shown`: https://smartbear.com/SmartBear/media/pdfs/11_Best_Practices_for_Peer_Code_Review.pdf
.. _`our mailing list`: https://mail.python.org/mailman/listinfo/cryptography-dev
.. _`doc8`: https://github.com/openstack/doc8