Use the new TLD of RTD.

README.rst

@@ -9,7 +9,7 @@
         :target: https://travis-ci.org/zopefoundation/zope.configuration
 
 .. image:: https://readthedocs.org/projects/zopeconfiguration/badge/?version=latest
-        :target: http://zopeconfiguration.readthedocs.org/en/latest/
+        :target: http://zopeconfiguration.readthedocs.io/en/latest/
         :alt: Documentation Status
 
 The Zope configuration system provides an extensible system for
@@ -20,6 +20,6 @@ configuration system provide configuration directives in some
 language that express configuration choices. The intent is that the
 language be pluggable.  An XML language is provided by default.
 
-Please see http://zopeconfiguration.readthedocs.org/en/latest/ for the documentation.
+Please see http://zopeconfiguration.readthedocs.io/en/latest/ for the documentation.