Fixed #15566 - Documented that update() doesn't honor DateField.auto_now

Thanks Shabda Raaj for the draft patch.

docs/howto/custom-model-fields.txt

@@ -181,10 +181,10 @@ card values plus their suits; 104 characters in total.
     Many of Django's model fields accept options that they don't do anything
     with. For example, you can pass both
     :attr:`~django.db.models.Field.editable` and
-    :attr:`~django.db.models.Field.auto_now` to a
+    :attr:`~django.db.models.DateField.auto_now` to a
     :class:`django.db.models.DateField` and it will simply ignore the
     :attr:`~django.db.models.Field.editable` parameter
-    (:attr:`~django.db.models.Field.auto_now` being set implies
+    (:attr:`~django.db.models.DateField.auto_now` being set implies
     ``editable=False``). No error is raised in this case.
 
     This behavior simplifies the field classes, because they don't need to
@@ -516,8 +516,8 @@ for the first time, the ``add`` parameter will be ``True``, otherwise it will be
 You only need to override this method if you want to preprocess the value
 somehow, just before saving. For example, Django's
 :class:`~django.db.models.DateTimeField` uses this method to set the attribute
-correctly in the case of :attr:`~django.db.models.Field.auto_now` or
-:attr:`~django.db.models.Field.auto_now_add`.
+correctly in the case of :attr:`~django.db.models.DateField.auto_now` or
+:attr:`~django.db.models.DateField.auto_now_add`.
 
 If you do override this method, you must return the value of the attribute at
 the end. You should also update the model's attribute if you make any changes

docs/topics/db/queries.txt

@@ -968,11 +968,12 @@ Be aware that the ``update()`` method is converted directly to an SQL
 statement. It is a bulk operation for direct updates. It doesn't run any
 :meth:`~django.db.models.Model.save` methods on your models, or emit the
 ``pre_save`` or ``post_save`` signals (which are a consequence of calling
-:meth:`~django.db.models.Model.save`). If you want to save every item in a
-:class:`~django.db.models.query.QuerySet` and make sure that the
-:meth:`~django.db.models.Model.save` method is called on each instance, you
-don't need any special function to handle that. Just loop over them and call
-:meth:`~django.db.models.Model.save`::
+:meth:`~django.db.models.Model.save`), or honor the
+:attr:`~django.db.models.DateField.auto_now` field option.
+If you want to save every item in a :class:`~django.db.models.query.QuerySet`
+and make sure that the :meth:`~django.db.models.Model.save` method is called on
+each instance, you don't need any special function to handle that. Just loop
+over them and call :meth:`~django.db.models.Model.save`::
 
     for item in my_queryset:
         item.save()