MS Windows README added, linked to main README

README.md added 'Running in MS Windows' section, linking to separate new file README_MS_Windows.md This version addresses the problem where WSL2 likes to close all WSL2 processes after 15sec. It uses WSL2 Ubuntu 22, flatpak, a startup script to set a few key environment variables, and the GWSL X-Windows server for Windows. It includes using GWSL's ability to create a Windows icon to run a WSL2 application from the Start Menu, as well as start dbus. The drawback is at every start, the user's sudo password must be entered. An alternative would be to require the user to open a WSL2 terminal window, and leave it open for the duration of running Cambalache.