whatsnew: add porting note for pyvenv --without-pip.
Remove unused sphinx-build.py entry script.
Closes #20090: update Doc/README and the error message in sphinx-build.py to make
it clear that any Python 3.x is not usable with the checked out Sphinx.
Closes #20090: update Doc/README.txt for the changes in the 3.4 branch.
whatsnew: ChainMap.new_child *m* argument.

And NEWS entry.
whatsnew: Message.set_param *replace*, Policy.content_manager.

Also cleaned up the email section and fixed some markup bugs in the
email docs.
whatsnew: filecmp.DEFAULT_IGNORES (#15442)
whatsnew: total_ordering supports NotImplemented (#10042)
whatsnew: logging.fileConfig accepts ConfigParser instances. (#16110)

And missing NEWS entry.
whatsnew: logging.config.listen *verify* (#15452).
whatsnew: remove redundant entry.
whatsnew: multiprocessing start methods and context (#8713 and #18999)

Also tweaked the docs a bit to use our standard style for
versionadded/changed.  (I'm guessing there are other places
in the multiprocessing docs where similar tweaks should be made.)
whatsnew: PEP 424 implementation.
whatsnew: json dump-with-indent whitespace change (#16333).
whatsnew: os.open O_TMPFILE (#18673).
whatsnew: os.open O_PATH and O_TMPFILE.
whatsnew: shutil copyfile SameFileError (#1492704)
whatsnew: urllib Request objects are now reusable.

#16464, #17485, #17272.
whatsnew: deprecation of ElementTree XMLParser *html* and iterparse *parser*.

#17741
whatsnew: take credit.

They aren't all my words, but most of them are :).