Update documentation for Python 3

README.md

@@ -68,17 +68,17 @@ pip install virtualenv
 #### On Debian-based Linuxes
 
 ``` sh
-sudo apt install python-virtualenv python-pip
+sudo apt install python3-virtualenv python3-pip
 ./mach bootstrap
 ```
 
-If you are on Ubuntu 20.04 or higher you need to do the following to install the missing python2 bits:
+If you are on Ubuntu 20.04 or higher you need to do the following to install the missing python3 bits:
 
 ```sh
 curl https://bootstrap.pypa.io/get-pip.py -sSf -o get-pip.py
-python2 get-pip.py
-python2 -m pip install virtualenv
-sudo apt install python-dev
+python3 get-pip.py
+python3 -m pip install virtualenv
+sudo apt install python3-dev
 ```
 
 If `./mach bootstrap` doesn't work, file a bug, and, run the commands below:
@@ -158,14 +158,14 @@ export LIBCLANG_PATH=/opt/rh/llvm-toolset-7/root/usr/lib64
 sudo zypper install libX11-devel libexpat-devel Mesa-libEGL-devel Mesa-libGL-devel cabextract cmake \
     dbus-1-devel fontconfig-devel freetype-devel gcc-c++ git glib2-devel gperf \
     harfbuzz-devel libXcursor-devel libXi-devel libXmu-devel libXrandr-devel libopenssl-devel \
-    python-pip python-virtualenv rpm-build ccache llvm-clang libclang autoconf213 gstreamer-devel \
+    python3-pip python3-virtualenv rpm-build ccache llvm-clang libclang autoconf213 gstreamer-devel \
     gstreamer-plugins-base-devel gstreamer-plugins-bad-devel
 ```
 
 #### On Arch Linux
 
 ``` sh
-sudo pacman -S --needed base-devel git python2 python2-virtualenv python2-pip mesa cmake libxmu \
+sudo pacman -S --needed base-devel git python python-virtualenv python-pip mesa cmake libxmu \
     pkg-config ttf-fira-sans harfbuzz ccache llvm clang autoconf2.13 gstreamer gstreamer-vaapi \
     gst-plugins-base gst-plugins-good gst-plugins-bad
 ```
@@ -188,24 +188,15 @@ export LIBCLANG_PATH=$(llvm-config --prefix)/lib64
 
 #### On Windows (MSVC)
 
-1. Install Python 2.7 for Windows (https://www.python.org/downloads/release/python-2716/). The Windows x86-64 MSI installer is fine. This is required for the build system execution and many dependencies.
+1. Install Python 3.9 for Windows (https://www.python.org/downloads/release/python-392/). The Windows x86-64 MSI installer is fine. This is required in order to build the JavaScript engine, SpiderMonkey.
 
-You should change the installation to install the "Add python.exe to Path" feature.
-
-You will also need to set the `PYTHON2` environment variable, e.g., to 'C:\Python27\python.exe' by doing:
+You will also need to set the `PYTHON3` environment variable, e.g., to 'C:\Python39\python.exe' by doing:
 ```
-setx PYTHON2 "C:\Python27\python.exe" /m
-```
-
-2. Install Python 3.7 for Windows (https://www.python.org/downloads/release/python-374/). The Windows x86-64 MSI installer is fine. This is required in order to build the JavaScript engine, SpiderMonkey.
-
-You will also need to set the `PYTHON3` environment variable, e.g., to 'C:\Python37\python.exe' by doing:
-```
-setx PYTHON3 "C:\Python37\python.exe" /m
+setx PYTHON3 "C:\Python39\python.exe" /m
 ```
 The `/m` will set it system-wide for all future command windows.
 
-3. Install virtualenv.
+2. Install virtualenv.
 
  In a normal Windows Shell (cmd.exe or "Command Prompt" from the start menu), do:
  ```
@@ -213,7 +204,7 @@ pip install virtualenv
 ```
  If this does not work, you may need to reboot for the changed PATH settings (by the python installer) to take effect.
 
-4. Install the most recent [GStreamer](https://gstreamer.freedesktop.org/data/pkg/windows/) MSVC packages. You need to download the two `.msi` files for your platform from the [GStreamer](https://gstreamer.freedesktop.org/data/pkg/windows/) website and install them. The currently recommended version is 1.16.0. i.e.:
+3. Install the most recent [GStreamer](https://gstreamer.freedesktop.org/data/pkg/windows/) MSVC packages. You need to download the two `.msi` files for your platform from the [GStreamer](https://gstreamer.freedesktop.org/data/pkg/windows/) website and install them. The currently recommended version is 1.16.0. i.e.:
 
 - [gstreamer-1.0-msvc-x86_64-1.16.0.msi](https://gstreamer.freedesktop.org/data/pkg/windows/1.16.0/gstreamer-1.0-msvc-x86_64-1.16.0.msi)
 - [gstreamer-1.0-devel-msvc-x86_64-1.16.0.msi](https://gstreamer.freedesktop.org/data/pkg/windows/1.16.0/gstreamer-1.0-devel-msvc-x86_64-1.16.0.msi)
@@ -222,10 +213,10 @@ Note that the MinGW binaries will not work, so make sure that you install the MS
 
 Note that you should ensure that _all_ components are installed from gstreamer, as we require many of the optional libraries that are not installed by default.
 
-5. Install Git for Windows (https://git-scm.com/download/win). DO allow it to add git.exe to the PATH (default
+4. Install Git for Windows (https://git-scm.com/download/win). DO allow it to add git.exe to the PATH (default
 settings for the installer are fine).
 
-6. Install Visual Studio Community 2017 (https://www.visualstudio.com/vs/community/). You MUST add "Visual C++" to the
+5. Install Visual Studio Community 2017 (https://www.visualstudio.com/vs/community/). You MUST add "Visual C++" to the
 list of installed components as well as the "Windows Universal C runtime." They are not on by default. Visual Studio 2017 MUST installed to the default location or mach.bat will not find it.
 
 Note that version is hard to download online and is easier to install via [Chocolatey](https://chocolatey.org/install#installing-chocolatey) with:
@@ -254,7 +245,7 @@ linker = "lld-link.exe"
 
 > If you encountered errors with the environment above, do the following for a workaround:
 > 1.  Download and install [Build Tools for Visual Studio 2017](https://www.visualstudio.com/thank-you-downloading-visual-studio/?sku=BuildTools&rel=15)
-> 2.  Install `python2.7 x86-x64` and `virtualenv`
+> 2.  Install `python3.9 x86-x64` and `virtualenv`
 > 3.  Run `mach.bat build -d`.
 
 >If you have troubles with `x64 type` prompt as `mach.bat` set by default: