please add to compile instructions (windows)

[jengert]

on the compile instructions https://github.com/supertuxkart/stk-code/blob/master/README.md#building-from-source installing VS on windows does not automatically install the compiler, you need to start the studio, when you go to make a new project of type general C++, it prompts you to install them. Otherwise cmake errors out saying it can not find the compilers.

[Auria]

Hi,

well I think installing the compiler is kind of out of the scope of what STK needs to document, it may be better to simply refer to microsoft's documentation if someone has questions regarding the installation of visual studio? (also, I don't remember needing to do that - I believe during installation you can select which packages you are interested in, and at this time you can check "c++")