Issue #28089: Document TCP_NODELAY in asyncio

Initial patch by Mariatta Wijaya.

Doc/library/asyncio-protocol.rst

@@ -25,6 +25,9 @@ the transport's kind.
 
 The transport classes are :ref:`not thread safe <asyncio-multithreading>`.
 
+.. versionchanged:: 3.6
+   The socket option ``TCP_NODELAY`` is now set by default.
+
 
 BaseTransport
 -------------

Doc/whatsnew/3.6.rst

@@ -875,6 +875,9 @@ Notable changes in the :mod:`asyncio` module since Python 3.5.0
   but that use asyncio to handle them.
   (Contributed by Jim Fulton in :issue:`27392`.)
 
+* ``TCP_NODELAY`` flag is now set for all TCP transports by default.
+  (Contributed by Yury Selivanov in :issue:`27456`.)
+
 
 binascii
 --------