def append_docstring_attributes(docstring, locals):
    """Manually appends class' ``docstring`` with its attribute docstrings.
    For example::

        class Entity(object):
            # ...

            __doc__ = append_docstring_attributes(
                __doc__,
                dict((k, v) for k, v in locals()
                            if isinstance(v, MyDescriptor))
            )

    :param docstring: class docstring to be appended
    :type docstring: :class:`str`
    :param locals: attributes dict
    :type locals: :class:`~typing.Mapping`\ [:class:`str`, :class:`object`]
    :returns: appended docstring
    :rtype: :class:`str`

    """
    docstring = docstring or ''
    for attr, val in locals.items():
        doc = val.__doc__
        if not doc:
            continue
        doc = get_minimum_indent(doc) + doc
        lines = ['   ' + l for l in textwrap.dedent(doc).splitlines()]
        docstring = append_docstring(
            docstring,
            '',
            '.. attribute:: ' + attr,
            '',
            *lines
        )
    return docstring