Update README.rst (#143)

Author: Yourun-proger

README.rst

@@ -113,4 +113,4 @@ suggestion. For more information check our contribution `guidelines`_.
 .. _Github issue: https://github.com/vitalk/pytest-flask/issues
 .. _package documentation: http://pytest-flask.readthedocs.org/en/latest/
 .. _guidelines: https://github.com/pytest-dev/pytest-flask/blob/master/CONTRIBUTING.rst
-.. _application factory: https://flask.palletsprojects.com/en/1.1.x/patterns/appfactories/
+.. _application factory: https://flask.palletsprojects.com/patterns/appfactories/