Fixed #16929 - Documented how to extend UserAdmin with UserProfile fields; thanks charettes for the draft example.

docs/topics/auth.txt

@@ -650,6 +650,36 @@ the handler, if ``created`` is ``True``, create the associated user profile::
 .. seealso:: :doc:`/topics/signals` for more information on Django's signal
     dispatcher.
 
+Adding UserProfile fields to the admin
+--------------------------------------
+
+To add the UserProfile fields to the user page in the admin, define an
+:class:`~django.contrib.admin.InlineModelAdmin` (for this example, we'll use a
+:class:`~django.contrib.admin.StackedInline`) in your app's ``admin.py`` and
+add it to a ``UserAdmin`` class which is registered with the
+:class:`~django.contrib.auth.models.User` class::
+
+    from django.contrib import admin
+    from django.contrib.auth.admin import UserAdmin
+    from django.contrib.auth.models import User
+
+    from my_user_profile_app.models import UserProfile
+
+    # Define an inline admin descriptor for UserProfile model
+    # which acts a bit like a singleton
+    class UserProfileInline(admin.StackedInline):
+        model = UserProfile
+        can_delete = False
+        verbose_name_plural = 'profile'
+
+    # Define a new User admin
+    class UserAdmin(UserAdmin):
+        inlines = (UserProfileInline, )
+
+    # Re-register UserAdmin
+    admin.site.unregister(User)
+    admin.site.register(User, UserAdmin)
+
 Authentication in Web requests
 ==============================