[1.5.x] Minor edits to some recently-added admin docs.

    values defined in :attr:`ModelAdmin.readonly_fields` to be displayed as

    read-only.

    The ``fields`` option, unlike :attr:`~ModelAdmin.list_display`, may contain

    only field names of the model or the form specified by

    :attr:`~ModelAdmin.form`, not callables. However it *can* contain callables

    if they are defined in :attr:`~ModelAdmin.readonly_fields`.

    The ``fields`` option, unlike :attr:`~ModelAdmin.list_display`, may only

    contain names of fields on the model or the form specified by

    :attr:`~ModelAdmin.form`. It may contain callables only if they are listed

    in :attr:`~ModelAdmin.readonly_fields`.

    .. versionadded:: 1.4

            'fields': ('first_name', 'last_name', 'address', 'city', 'state'),

            }

        Just like with the :attr:`~ModelAdmin.fields` option, to display

        multiple fields on the same line, wrap those fields in their own

        tuple. In this example, the ``first_name`` and ``last_name`` fields

        will display on the same line::

        As with the :attr:`~ModelAdmin.fields` option, to display multiple

        fields on the same line, wrap those fields in their own tuple. In this

        example, the ``first_name`` and ``last_name`` fields will display on

        the same line::

            {

            'fields': (('first_name', 'last_name'), 'address', 'city', 'state'),

        ``fields`` can contain values defined in

        :attr:`~ModelAdmin.readonly_fields` to be displayed as read-only.

        If you add a callable name to ``fields``, the same rule applies as

        with :attr:`~ModelAdmin.fields` option: the callable must be

        specified in :attr:`~ModelAdmin.readonly_fields`.

        If you add the name of a callable to ``fields``, the same rule applies

        as with the :attr:`~ModelAdmin.fields` option: the callable must be

        listed in :attr:`~ModelAdmin.readonly_fields`.

    * ``classes``

        A list containing extra CSS classes to apply to the fieldset.