README: fix zip download and clone references

doc/README_Linux.md

@@ -79,8 +79,8 @@ This method is intended for experienced users, who may want to use opam to insta
   - OpenSuse:             sudo zypper in -t pattern devel_C_C++
 - For CentOS and possibly RHEL some additional steps are required, see [CentOS](#centos) below.
 - Get the Coq Platform scripts via either of these methods
-  - Most users should download and extract `https://github.com/coq/platform/archive/2021.09.zip`.
-  - Users which intend to contribute to Coq Platform should use `git clone --branch 2021.09 https://github.com/coq/platform.git`.
+  - Most users should download and extract `https://github.com/coq/platform/archive/refs/tags/2021.09.0.zip`.
+  - Users which intend to contribute to Coq Platform should use `git clone --branch 2021.09.0 https://github.com/coq/platform.git`.
 - Open a shell, navigate to the download folder and execute `coq_platform_make.sh`.
 - The system will ask for sudo permissions to install prerequisites *several times* so the script is not fully unattended but all installations of dependencies are done directly after the initialization of the opam switch.
 - In case the script aborts e.g. cause of internet issues, just rerun the script.

doc/README_Windows.md

@@ -18,8 +18,8 @@ A note to lecturers: it is easy to create a customized Windows installer from an
 This method is intended for experienced users, who may want to use opam to install additional packages, beyond the standard set provided by the Coq Platform, or who need an advanced working environment with a posix shell, make, dune, ...
 
 - Get the Coq Platform scripts via either of these methods
-  - Most users should download and extract `https://github.com/coq/platform/archive/2021.09.zip`.
-  - Users which intend to contribute to Coq Platform should use `git clone --branch 2021.09 https://github.com/coq/platform.git`.
+  - Most users should download and extract `https://github.com/coq/platform/archive/refs/tags/2021.09.0.zip`.
+  - Users which intend to contribute to Coq Platform should use `git clone --branch 2021.09.0 https://github.com/coq/platform.git`.
     Please note that the scripts are CR/LF sensitive, so if you use a Windows git client (not a Cygwin git) you should set `git config --global core.autocrlf false` - which is anyway a good idea.
 - Open a command window, navigate to the download folder and execute `coq_platform_make_windows.bat`
 - This will ask for the Cygwin installation path and setup a fresh Cygwin as build host (the created Coq is MinGW and runs without Cygwin).

doc/README_macOS.md

@@ -33,8 +33,8 @@ This method is intended for experienced users, who may want to use opam to insta
 - If you have neither Homebrew nor MacPorts installed, read the section [Homebrew and MacPorts](#homebrew-and-macports) below.
 - If you have Homebrew installed, read the section [Homebrew issues and workarounds](#homebrew-issues-and-workarounds) below.
 - Get the Coq Platform scripts via either of these methods
-  - Most users should download and extract `https://github.com/coq/platform/archive/2021.09.zip`.
-  - Users which intend to contribute to Coq Platform should use `git clone --branch 2021.09 https://github.com/coq/platform.git`.
+  - Most users should download and extract `https://github.com/coq/platform/archive/refs/tags/2021.09.0.zip`.
+  - Users which intend to contribute to Coq Platform should use `git clone --branch 2021.09.0 https://github.com/coq/platform.git`.
 - Open a shell, navigate to the download folder and execute `coq_platform_make.sh`.
 - If you are using MacPorts, the system will ask once for sudo permissions to install prerequisites after installing OCaml (5..20 minutes after script start).
 - In case the script aborts e.g. cause of internet issues, just rerun the script.