Update domain for Wagtail

wagtail/wagtail#7841

Author: RealOrangeOne

topics/wagtail/index.md

@@ -9,7 +9,7 @@ released: February 2014
 short_description: Wagtail is an open source CMS written in Python and
   built on the Django web framework.
 topic: wagtail
-url: https://wagtail.io/
+url: https://wagtail.org/
 wikipedia_url: https://en.wikipedia.org/wiki/Wagtail_(CMS)
 ---
 Wagtail is a free and open source content management system (CMS) written in Python. The project has a focus on developer friendliness as well as ease of use of its administration interface, translated in multiple languages.