Fixed #21212 -- Documented the reverse name for OneToOneField.

including all the options regarding :ref:`recursive <recursive-relationships>`

and :ref:`lazy <lazy-relationships>` relationships.

If you do not specify the the :attr:`~ForeignKey.related_name` argument for

the ``OneToOneField``, Django will use the lower-case name of the current model

as default value.

With the following example::

    from django.db import models

    from django.contrib.auth.models import User

    class MySpecialUser(models.Model):

        user = models.OneToOneField(User)

        supervisor = models.OneToOneField(User, related_name='supervisor_of')

your resulting ``User`` model will have the following attributes::

    >>> user = User.objects.get(pk=1)

    >>> hasattr(user, 'myspecialuser')

    True

    >>> hasattr(user, 'supervisor_of')

    True

.. _onetoone-arguments:

Additionally, ``OneToOneField`` accepts all of the extra arguments

    link back to the parent class, rather than the extra

    ``OneToOneField`` which would normally be implicitly created by

    subclassing.

See :doc:`One-to-one relationships </topics/db/examples/one_to_one>` for usage

examples of ``OneToOneField``.