[3.1.x] Fixed #32371 -- Doc'd jquery.init.js dependency for admin wid…

…gets.

Backport of 7b3ec6b from master

docs/ref/contrib/admin/index.txt

@@ -2172,7 +2172,10 @@ Django admin JavaScript makes use of the `jQuery`_ library.
 To avoid conflicts with user-supplied scripts or libraries, Django's jQuery
 (version 3.5.1) is namespaced as ``django.jQuery``. If you want to use jQuery
 in your own admin JavaScript without including a second copy, you can use the
-``django.jQuery`` object on changelist and add/edit views.
+``django.jQuery`` object on changelist and add/edit views. Also, your own admin
+forms or widgets depending on ``django.jQuery`` must specify
+``js=['admin/js/jquery.init.js', …]`` when :ref:`declaring form media assets
+<assets-as-a-static-definition>`.
 
 .. versionchanged:: 3.0