Fixed #5726 -- Documented that inspectdb doesn't detect defaults.

docs/ref/django-admin.txt

@@ -366,6 +366,11 @@ needed.
 ``inspectdb`` works with PostgreSQL, MySQL and SQLite. Foreign-key detection
 only works in PostgreSQL and with certain types of MySQL tables.
 
+Django doesn't create database defaults when a
+:attr:`~django.db.models.Field.default` is specified on a model field.
+Similarly, database defaults aren't translated to model field defaults or
+detected in any fashion by ``inspectdb``.
+
 By default, ``inspectdb`` creates unmanaged models. That is, ``managed = False``
 in the model's ``Meta`` class tells Django not to manage each table's creation,
 modification, and deletion. If you do want to allow Django to manage the