Update URLs for new RTD domain (#2879)
diff --git a/docs/development/c-bindings.rst b/docs/development/c-bindings.rst
index 993a4ab..cbd8fab 100644
--- a/docs/development/c-bindings.rst
+++ b/docs/development/c-bindings.rst
@@ -3,7 +3,7 @@
C bindings are bindings to C libraries, using cffi_ whenever possible.
-.. _cffi: https://cffi.readthedocs.org
+.. _cffi: https://cffi.readthedocs.io
Bindings live in :py:mod:`cryptography.hazmat.bindings`.
diff --git a/docs/faq.rst b/docs/faq.rst
index f00974b..76dc4f3 100644
--- a/docs/faq.rst
+++ b/docs/faq.rst
@@ -54,6 +54,6 @@
in ``cryptography`` 1.5.
.. _`NaCl`: https://nacl.cr.yp.to/
-.. _`PyNaCl`: https://pynacl.readthedocs.org
-.. _`WSGIApplicationGroup`: https://modwsgi.readthedocs.org/en/develop/configuration-directives/WSGIApplicationGroup.html
+.. _`PyNaCl`: https://pynacl.readthedocs.io
+.. _`WSGIApplicationGroup`: https://modwsgi.readthedocs.io/en/develop/configuration-directives/WSGIApplicationGroup.html
.. _`issue`: https://github.com/pyca/cryptography/issues
diff --git a/docs/hazmat/bindings/commoncrypto.rst b/docs/hazmat/bindings/commoncrypto.rst
index 4f58a6d..fd3d39a 100644
--- a/docs/hazmat/bindings/commoncrypto.rst
+++ b/docs/hazmat/bindings/commoncrypto.rst
@@ -26,5 +26,5 @@
functions, and access constants.
-.. _`CFFI`: https://cffi.readthedocs.org/
+.. _`CFFI`: https://cffi.readthedocs.io
.. _`CommonCrypto`: https://developer.apple.com/library/mac/documentation/Darwin/Reference/ManPages/man3/Common%20Crypto.3cc.html
diff --git a/docs/hazmat/bindings/openssl.rst b/docs/hazmat/bindings/openssl.rst
index 99cd7a4..8935093 100644
--- a/docs/hazmat/bindings/openssl.rst
+++ b/docs/hazmat/bindings/openssl.rst
@@ -44,6 +44,6 @@
because it has to acquire the GIL whenever any lock operations occur within
OpenSSL.
-.. _`CFFI`: https://cffi.readthedocs.org/
+.. _`CFFI`: https://cffi.readthedocs.io
.. _`OpenSSL`: https://www.openssl.org/
.. _`thread safety facilities`: https://www.openssl.org/docs/manmaster/crypto/threads.html