:handshake: Removed 'Django Sites' as it no longer exists. (#261)

Redirects to "https://www.rossp.org/blog/farewell-djangosites/?utm_source=djangosites.org&utm_medium=redirect&utm_campaign=djangosites-farewell" which has 

Current redirected page reads: "Farewell, Djangosites
Time for something new to take it’s place."

README.md

@@ -370,7 +370,6 @@ _A short list of Python packages that work well with Django._
 - [RealPython](https://realpython.com/tutorials/django/) - Many high-quality tutorials on Django.
 - [Mozilla Tutorial](https://developer.mozilla.org/en-US/docs/Learn/Server-side/Django) - Create a lending library app.
 - [Matt Layman](https://www.mattlayman.com) - Regular tutorials and deep-dives on Django topics.
-- [Django Sites](https://www.djangosites.org/) - Comprehensive listing of sites built with Django.
 - [Django Styleguide](https://github.com/HackSoftware/Django-Styleguide) - Styleguide for Django with best practices and examples.
 - [Django Template Tags and Filters](https://www.djangotemplatetagsandfilters.com/) - Additional docs on Django's 57 built-in template filters and 27 template tags.
 - [Django for Everybody](https://www.dj4e.com/) - A complete course for webdev beginners focused on Django.