pep-0492: Mention new ABC classes.

pep-0492.txt

@@ -696,6 +696,21 @@ New Standard Library Functions
   thread-specific.  See  `Debugging Features`_ for more details.
 
 
+New Abstract Base Classes
+-------------------------
+
+In order to allow better integration with existing frameworks (such as
+Tornado, see [13]_) and compilers (such as Cython, see [16]_), two new
+Abstract Base Classes (ABC) are added:
+
+* ``collections.abc.Awaitable`` ABC for *Future-like* classes, that
+  implement ``__await__`` method.
+
+* ``collections.abc.Coroutine`` ABC for *coroutine* objects, that
+  implement ``send(value)``, ``throw(type, exc, tb)``, and ``close()``
+  methods.
+
+
 Glossary
 ========
 
@@ -1314,6 +1329,9 @@ List of high-level changes and new protocols
 7. New ``CO_COROUTINE`` and ``CO_ITERABLE_COROUTINE`` bit flags for code
    objects.
 
+8. New ABCs: ``collections.abc.Awaitable`` and
+   ``collections.abc.Coroutine``.
+
 While the list of changes and new things is not short, it is important
 to understand, that most users will not use these features directly.
 It is intended to be used in frameworks and libraries to provide users
@@ -1396,10 +1414,13 @@ References
 
 .. [12] https://docs.python.org/3/reference/expressions.html#primaries
 
+.. [13] https://mail.python.org/pipermail/python-dev/2015-May/139851.html
+
 .. [14] https://mail.python.org/pipermail/python-dev/2015-May/139844.html
 
 .. [15] http://bugs.python.org/issue24017
 
+.. [16] https://github.com/python/asyncio/issues/233
 
 Acknowledgments
 ===============