move Django for APIs book to 4.0 section

README.md

@@ -348,6 +348,7 @@ _A short list of Python packages that work well with Django._
 _Django 4.0_
 - [Django for Beginners: Build websites with Python and Django](https://djangoforbeginners.com/)
 - [Boost Your Django DX](https://adamchainz.gumroad.com/l/byddx)
+- [Django for APIs: Build web APIs with Python and Django](https://djangoforapis.com/)
 
 _Django 3.2_
 - [Speed Up Your Django Tests](https://adamj.eu/tech/2020/05/04/new-book-speed-up-your-django-tests/)
@@ -355,7 +356,6 @@ _Django 3.2_
 - [A Wedge of Django: Covers Python 3.8 and Django 3.x](https://www.feldroy.com/books/a-wedge-of-django)
 
 _Django 3.1_
-- [Django for APIs: Build web APIs with Python and Django](https://djangoforapis.com/)
 - [Django for Professionals: Production websites with Python and Django](https://djangoforprofessionals.com/)
 
 _Django 3.0_