Add missing URL link to Modernize docs.
diff --git a/Doc/howto/pyporting.rst b/Doc/howto/pyporting.rst
index 59c127e..bd80dfd 100644
--- a/Doc/howto/pyporting.rst
+++ b/Doc/howto/pyporting.rst
@@ -379,7 +379,7 @@
.. _cheat sheet: http://python-future.org/compatible_idioms.html
.. _coverage.py: https://pypi.python.org/pypi/coverage
.. _Futurize: http://python-future.org/automatic_conversion.html
-.. _Modernize:
+.. _Modernize: http://python-modernize.readthedocs.org/en/latest/
.. _Porting to Python 3: http://python3porting.com/
.. _Pylint: https://pypi.python.org/pypi/pylint
.. _Python 3 Q & A: http://ncoghlan-devs-python-notes.readthedocs.org/en/latest/python3/questions_and_answers.html