Fixed #10367: Added note to generic-relation docs explaining when it's...

    >>> b.tags.all()

    [<TaggedItem: django>, <TaggedItem: python>]

If you don't add the reverse relationship, you can do the lookup manually::

Just as :class:`django.contrib.contenttypes.generic.GenericForeignKey`

accepts the names of the content-type and object-ID fields as

arguments, so too does ``GenericRelation``; if the model which has the

generic foreign key is using non-default names for those fields, you

must pass the names of the fields when setting up a

``GenericRelation`` to it. For example, if the ``TaggedItem`` model

referred to above used fields named ``content_type_fk`` and

``object_primary_key`` to create its generic foreign key, then a

``GenericRelation`` back to it would need to be defined like so::

    tags = generic.GenericRelation('content_type_fk', 'object_primary_key')

Of course, if you don't add the reverse relationship, you can do the

same types of lookups manually::

    >>> b = Bookmark.objects.get(url='http://www.djangoproject.com/')

    >>> bookmark_type = ContentType.objects.get_for_model(b)