Issue #28089: Document TCP_NODELAY in asyncio

Initial patch by Mariatta Wijaya.
diff --git a/Doc/library/asyncio-protocol.rst b/Doc/library/asyncio-protocol.rst
index c0342f7..3fbf510 100644
--- a/Doc/library/asyncio-protocol.rst
+++ b/Doc/library/asyncio-protocol.rst
@@ -25,6 +25,9 @@
 
 The transport classes are :ref:`not thread safe <asyncio-multithreading>`.
 
+.. versionchanged:: 3.6
+   The socket option ``TCP_NODELAY`` is now set by default.
+
 
 BaseTransport
 -------------
diff --git a/Doc/whatsnew/3.6.rst b/Doc/whatsnew/3.6.rst
index ddca2ef..0187f94 100644
--- a/Doc/whatsnew/3.6.rst
+++ b/Doc/whatsnew/3.6.rst
@@ -875,6 +875,9 @@
   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
 --------