add non-WSL Windows tab to dx installation page

[bates64]

https://docs.starhaven.dev/develop/dx/

1. install git(hub for windows)
2. clone papermario-dx
3. double-click build.bat
4. (windows 7 only) download and unzip the toolchain as instructed

and remove the line "If you are on Windows 7 or 8, use Star Rod Classic (DX is not supported)."