Improve the documentation on how to get started with the Qt development on windows

Also the page here (http://doc.qt.io/qt-5/windows-requirements.html) is listing what is needed it is not very helpful to actually get started as the Qt installer doesn't complain about missing compilers at all.

I just tried to get an env running with Visual Studio 2017 and stumbled over a lot of things (including a broken vcvarsall.bat from VS).

I think it would be helpful to reususe the term MSVC also in the documentation as that is used in the installer as well and also in the mkspec. In addition it would help to provide atleast a list of components the user needs to install from VS as it's quite big nowadays.

E.g. Select the template for C++ development but make sure you have the following selected as well:

Windows 10 SDK (this is needed to get the rc.exe binary)
MS 2015 Build tools (to get the msvc-2015 copmiler, needed for some prebuild qt environments)

Without selecting the right packages you can get easily in a situation where no compilers are installed or some additional tools are missing. I can't provide the list myself as i just installed a lot by try and error to get it up and i might have installed way to much...