add explaination on all-in-one offline installer.

source/SpinalHDL/Getting Started/Install and setup.rst

@@ -145,6 +145,15 @@ when asked agree to an update of your ``PATH`` variable. Reboot to force an upda
 This is sufficient for generating hardware. For simulation continue with either choice below.
 In case you want to build the tools yourself have a look at the legacy simulation tool :ref:`installation instructions <sim backend install>`.
 
+.. note::
+   An All-in-One solution is available to install and run SpinalHDL with Verilator simulation and formal verification via SymbiYosys.
+   Download `it <https://github.com/Readon/msys2-installer/releases>`_ and install the environment anywhere on your disk.
+   Start the build environment by clicking on the MSYS2-MINGW64 icon in the Start menu and use the MSYS2 default console. 
+   An alternative is to use the Windows Terminal or a Tabby-like application and use the startup command ``%MSYS2_ROOT%\msys2_shell.cmd -defterm -here -no-start -mingw64``, where the ``%MSYS2_ROOT%`` is the location of the msys2 installation.
+   It is worth noting that if you want to use it offline, you should carefully select the libraries that the project depends on, otherwise you will need to download the packages manually.
+   See the README for the repos for more details.
+
+
 MSYS2 verilator for simulation
 ^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^