Windows instructions

[rofrol]

I needed to install this https://releases.llvm.org/download.html for clang.

[rofrol]

Windows SDK is also needed otherwise there would be error like:

fatal error LNK1181: cannot open input file 'd3d12.lib'

https://stackoverflow.com/questions/59648046/unable-to-compile-rust-program-lnk1181-cannot-open-input-file-c-program-obj/63505627#63505627