Update macOS installer ReadMe for 3.8.7 and Big Sur (GH-23882)

Author: ned-deily

Mac/BuildScript/resources/ReadMe.rtf

@@ -1,6 +1,6 @@
 {\rtf1\ansi\ansicpg1252\cocoartf2513
-\cocoatextscaling0\cocoaplatform0{\fonttbl\f0\fswiss\fcharset0 Helvetica;\f1\fswiss\fcharset0 Helvetica-Bold;\f2\fswiss\fcharset0 Helvetica-Oblique;
-\f3\fmodern\fcharset0 CourierNewPSMT;}
+\cocoatextscaling0\cocoaplatform0{\fonttbl\f0\fswiss\fcharset0 Helvetica;\f1\fswiss\fcharset0 Helvetica-Bold;\f2\fmodern\fcharset0 CourierNewPSMT;
+\f3\fswiss\fcharset0 Helvetica-Oblique;}
 {\colortbl;\red255\green255\blue255;}
 {\*\expandedcolortbl;;}
 \margl1440\margr1440\vieww13380\viewh14600\viewkind0
@@ -10,25 +10,37 @@
 \
 \pard\tx720\tx1440\tx2160\tx2880\tx3600\tx4320\tx5040\tx5760\tx6480\tx7200\tx7920\tx8640\pardirnatural\partightenfactor0
 
-\f1\b \cf0 \ul \ulc0 Certificate verification and OpenSSL\
+\f1\b \cf0 \ul \ulc0 macOS 11 Big Sur not fully supported\
+
+\f0\b0 \ulnone \
+Python 3.8.7 is not yet fully supported on macOS 11 Big Sur.  It will install on macOS 11 Big Sur and will run on Apple Silicon Macs using Rosetta 2 translation.  But a few features do not work correctly, most noticeably those involving searching for system libraries such as 
+\f2 ctypes.util.find_library()
+\f0  and in 
+\f2 Distutils
+\f0 .  Python 3.9.1 or later provides full support for Big Sur and Apple Silicon Macs, including building natively on Apple Silicon Macs and support for 
+\f2 universal2
+\f0  binaries\
+\
+
+\f1\b \ul Certificate verification and OpenSSL\
 
 \f0\b0 \ulnone \
 This package includes its own private copy of OpenSSL 1.1.1.   The trust certificates in system and user keychains managed by the 
-\f2\i Keychain Access 
+\f3\i Keychain Access 
 \f0\i0 application and the 
-\f2\i security
+\f3\i security
 \f0\i0  command line utility are not used as defaults by the Python 
-\f3 ssl
+\f2 ssl
 \f0  module.  A sample command script is included in 
-\f3 /Applications/Python 3.8
+\f2 /Applications/Python 3.8
 \f0  to install a curated bundle of default root certificates from the third-party 
-\f3 certifi
+\f2 certifi
 \f0  package ({\field{\*\fldinst{HYPERLINK "https://pypi.org/project/certifi/"}}{\fldrslt https://pypi.org/project/certifi/}}).  Double-click on 
-\f3 Install Certificates
+\f2 Install Certificates
 \f0  to run it.\
 \
 The bundled 
-\f3 pip
+\f2 pip
 \f0  has its own default certificate store for verifying download connections.\
 \
 
@@ -60,26 +72,26 @@ Python 2.7 end-of-life [changed in 3.8.4]\
 \
 
 \f0\b0 \ulnone Python 2.7 has now reached end-of-life. As of Python 3.8.4, the 
-\f3 Python Launcher
+\f2 Python Launcher
 \f0  app now has 
-\f3 python3
+\f2 python3
 \f0  factory defaults.  Also, the 
-\f3 Current
+\f2 Current
 \f0  link in the 
-\f3 /Library/Frameworks/Python.framework/Versions
+\f2 /Library/Frameworks/Python.framework/Versions
 \f0  directory is now updated to point to the Python 3 being installed; previously, only Python 2 installs updated 
-\f3 Current
+\f2 Current
 \f0 .  This change might affect developers using the framework to embed Python in their applications.  If another version is desired for embedding, the 
-\f3 Current
+\f2 Current
 \f0  symlink can be changed manually without affecting 3.8.x behavior.\
 
 \f1\b \ul \
 Other changes\
 
 \f0\b0 \ulnone \
 For other changes in this release, see the 
-\f2\i What's new
+\f3\i What's new
 \f0\i0  section in the {\field{\*\fldinst{HYPERLINK "https://www.python.org/doc/"}}{\fldrslt Documentation Set}} for this release and its 
-\f2\i Release Notes
+\f3\i Release Notes
 \f0\i0  link at {\field{\*\fldinst{HYPERLINK "https://www.python.org/downloads/"}}{\fldrslt https://www.python.org/downloads/}}.\
 }