Decouple these docs from properties

Fixes #177

docs/examples.rst

@@ -98,24 +98,6 @@ This is useful in times when you want to enhance classes that are not yours (nic
    >>> SomethingFromSomeoneElse(1)
    SomethingFromSomeoneElse(x=1)
 
-Or if you want to use properties:
-
-.. doctest::
-
-   >>> @attr.s(these={"_x": attr.ib()})
-   ... class ReadOnlyXSquared(object):
-   ...    @property
-   ...    def x(self):
-   ...       return self._x ** 2
-   >>> rox = ReadOnlyXSquared(x=5)
-   >>> rox
-   ReadOnlyXSquared(_x=5)
-   >>> rox.x
-   25
-   >>> rox.x = 6
-   Traceback (most recent call last):
-      ...
-   AttributeError: can't set attribute
 
 `Subclassing <https://www.youtube.com/watch?v=3MNVP9-hglc>`_ is bad for you, but ``attrs`` will still do what you'd hope for:
 

src/attr/_make.py

@@ -235,10 +235,10 @@ def attributes(maybe_cls=None, these=None, repr_ns=None,
     :param these: A dictionary of name to :func:`attr.ib` mappings.  This is
         useful to avoid the definition of your attributes within the class body
         because you can't (e.g. if you want to add ``__repr__`` methods to
-        Django models) or don't want to (e.g. if you want to use
-        :class:`properties <property>`).
+        Django models) or don't want to.
 
-        If *these* is not ``None``, the class body is *ignored*.
+        If *these* is not ``None``, ``attrs`` will *not* search the class body
+        for attributes.
 
     :type these: :class:`dict` of :class:`str` to :func:`attr.ib`