Add MIT license to d3dx12.h: issue #77
Add MIT license to d3dx12.h: issue #77

Missed a file.

Samana/DirectX-Graphics-Samples,Microsoft/DirectX-Graphics-Samples,mattlee78/DirectX-Graphics-Samples,mattlee78/DirectX-Graphics-Samples,baesky/DirectX-Graphics-Samples,Samana/DirectX-Graphics-Samples,vanish87/DirectX-Graphics-Samples,SuperWangKai/DirectX-Graphics-Samples,KevindeQ/DirectX-Graphics-Samples,vanish87/DirectX-Graphics-Samples,SuperWangKai/DirectX-Graphics-Samples,baesky/DirectX-Graphics-Samples,SuperWangKai/DirectX-Graphics-Samples,Microsoft/DirectX-Graphics-Samples,KevindeQ/DirectX-Graphics-Samples,baesky/DirectX-Graphics-Samples,KevindeQ/DirectX-Graphics-Samples,Microsoft/DirectX-Graphics-Samples