Better README.md for dlang.org

[Jonathan M Davis via Digitalmars-d]

On Monday, January 19, 2015 15:14:16 Andrei Alexandrescu via Digitalmars-d wrote:
> https://github.com/D-Programming-Language/dlang.org/blob/master/README.md
>
> 1. If instructions don't work for you, reply here.
>
> 2. Additions for Windows would be welcome. FWIW I think the Windows
> makefile suffers from a bit of bitrot.

The windows makefile suffers from using an inferior version of make to
what's on the POSIX systems.

- Jonathan M Davis