Sync LICENSE with CPython (#205)

CHANGELOG.md

@@ -1,5 +1,8 @@
 # Unreleased
 
+- Sync the repository's LICENSE file with that of CPython.
+  `typing_extensions` is distributed under the same license as
+  CPython itself.
 - Skip a problematic test on Python 3.12.0b1. The test fails on 3.12.0b1 due to
   a bug in CPython, which will be fixed in 3.12.0b2. The
   `typing_extensions` test suite now passes on 3.12.0b1.

LICENSE

@@ -2,12 +2,12 @@ A. HISTORY OF THE SOFTWARE
 ==========================
 
 Python was created in the early 1990s by Guido van Rossum at Stichting
-Mathematisch Centrum (CWI, see http://www.cwi.nl) in the Netherlands
+Mathematisch Centrum (CWI, see https://www.cwi.nl) in the Netherlands
 as a successor of a language called ABC.  Guido remains Python's
 principal author, although it includes many contributions from others.
 
 In 1995, Guido continued his work on Python at the Corporation for
-National Research Initiatives (CNRI, see http://www.cnri.reston.va.us)
+National Research Initiatives (CNRI, see https://www.cnri.reston.va.us)
 in Reston, Virginia where he released several versions of the
 software.
 
@@ -19,7 +19,7 @@ https://www.python.org/psf/) was formed, a non-profit organization
 created specifically to own Python-related Intellectual Property.
 Zope Corporation was a sponsoring member of the PSF.
 
-All Python releases are Open Source (see http://www.opensource.org for
+All Python releases are Open Source (see https://opensource.org for
 the Open Source Definition).  Historically, most, but not all, Python
 releases have also been GPL-compatible; the table below summarizes
 the various releases.
@@ -59,6 +59,17 @@ direction to make these releases possible.
 B. TERMS AND CONDITIONS FOR ACCESSING OR OTHERWISE USING PYTHON
 ===============================================================
 
+Python software and documentation are licensed under the
+Python Software Foundation License Version 2.
+
+Starting with Python 3.8.6, examples, recipes, and other code in
+the documentation are dual licensed under the PSF License Version 2
+and the Zero-Clause BSD license.
+
+Some software incorporated into Python is under different licenses.
+The licenses are listed with code falling under that license.
+
+
 PYTHON SOFTWARE FOUNDATION LICENSE VERSION 2
 --------------------------------------------
 
@@ -73,7 +84,7 @@ analyze, test, perform and/or display publicly, prepare derivative works,
 distribute, and otherwise use Python alone or in any derivative version,
 provided, however, that PSF's License Agreement and PSF's notice of copyright,
 i.e., "Copyright (c) 2001, 2002, 2003, 2004, 2005, 2006, 2007, 2008, 2009, 2010,
-2011, 2012, 2013, 2014, 2015, 2016, 2017, 2018, 2019, 2020, 2021, 2022 Python Software Foundation;
+2011, 2012, 2013, 2014, 2015, 2016, 2017, 2018, 2019, 2020, 2021, 2022, 2023 Python Software Foundation;
 All Rights Reserved" are retained in Python alone or in any derivative version
 prepared by Licensee.
 
@@ -252,3 +263,17 @@ FOR ANY SPECIAL, INDIRECT OR CONSEQUENTIAL DAMAGES OR ANY DAMAGES
 WHATSOEVER RESULTING FROM LOSS OF USE, DATA OR PROFITS, WHETHER IN AN
 ACTION OF CONTRACT, NEGLIGENCE OR OTHER TORTIOUS ACTION, ARISING OUT
 OF OR IN CONNECTION WITH THE USE OR PERFORMANCE OF THIS SOFTWARE.
+
+ZERO-CLAUSE BSD LICENSE FOR CODE IN THE PYTHON DOCUMENTATION
+----------------------------------------------------------------------
+
+Permission to use, copy, modify, and/or distribute this software for any
+purpose with or without fee is hereby granted.
+
+THE SOFTWARE IS PROVIDED "AS IS" AND THE AUTHOR DISCLAIMS ALL WARRANTIES WITH
+REGARD TO THIS SOFTWARE INCLUDING ALL IMPLIED WARRANTIES OF MERCHANTABILITY
+AND FITNESS. IN NO EVENT SHALL THE AUTHOR BE LIABLE FOR ANY SPECIAL, DIRECT,
+INDIRECT, OR CONSEQUENTIAL DAMAGES OR ANY DAMAGES WHATSOEVER RESULTING FROM
+LOSS OF USE, DATA OR PROFITS, WHETHER IN AN ACTION OF CONTRACT, NEGLIGENCE OR
+OTHER TORTIOUS ACTION, ARISING OUT OF OR IN CONNECTION WITH THE USE OR
+PERFORMANCE OF THIS SOFTWARE.