Fixed #21908 -- Added example usage for ModelAdmin.get_inline_instances().

Thanks matt at schinckel.net for the suggestion.

docs/ref/contrib/admin/index.txt

@@ -1393,7 +1393,12 @@ templates used by the :class:`ModelAdmin` views:
     ``obj`` being edited (or ``None`` on an add form) and is expected to return
     a ``list`` or ``tuple`` of :class:`~django.contrib.admin.InlineModelAdmin`
     objects, as described below in the :class:`~django.contrib.admin.InlineModelAdmin`
-    section.
+    section. For example, the following would return inlines without the default
+    filtering based on add, change, and delete permissions::
+
+        class MyModelAdmin(admin.ModelAdmin):
+            def get_inline_instances(request, obj=None):
+                return [inline(self.model, self.admin_site) for inline in self.inlines]
 
 .. method:: ModelAdmin.get_urls()