DOC: remove left-over piece discussing binops

The text had been changed following the suggestion of @njsmith, but somehow I had forgotten to delete the original.
numpy · charris · Apr 27, 2017 · Nov 6, 2016 · Nov 9, 2016 · Nov 12, 2016
commit 856da73546da7adf8511a1d2cf83c23db171f26b
diff --git a/doc/source/reference/arrays.classes.rst b/doc/source/reference/arrays.classes.rst
@@ -88,17 +88,6 @@ NumPy provides several hooks that classes can customize:
    unless another class also provides a :func:`__array_ufunc__` method
    which knows what to do with your class).
 
-   The presence of :func:`__array_ufunc__` also influences how binary
-   and comparison operators are dealt with, such as ``__add__``,
-   ``__gt__``, etc.  If it is not :obj:`None`, the assumption is that
-   your code can handle such operations via the ufunc mechanism, and
-   hence forward methods on :class:`ndarray` will call the ufuncs
-   unconditionally (i.e., even if your class has defined reverse
-   methods such as ``__radd__``, ``__le__``, etc.). If
-   ``__array_ufunc__ = None``, however, forward methods on
-   :class:`ndarray` will unconditionally return :obj:`NotImplemented`,
-   so that your reverse methods will get called.
-
    The presence of :func:`__array_ufunc__` also influences how
    :class:`ndarray` handles binary operations like ``arr + obj`` and ``arr
    < obj`` when ``arr`` is an :class:`ndarray` and ``obj`` is an instance