Fix d3dx12.h readme formatting

Author: sebmerry

Libraries/D3DX12/readme.md

@@ -1,5 +1,5 @@
 # The D3D12 Helper Library
 
-The D3D12 Helper Library, d3dx12.h, has moved to the official Direct3D header repository, microsoft/DirectX-Headers:
-[Repository](https://github.com/microsoft/DirectX-Headers)
-[Header](https://github.com/microsoft/DirectX-Headers/blob/main/include/directx/d3dx12.h)
+The D3D12 Helper Library, d3dx12.h, has moved to the official Direct3D header repository, **microsoft/DirectX-Headers**:
+* [Repository](https://github.com/microsoft/DirectX-Headers)
+* [Header](https://github.com/microsoft/DirectX-Headers/blob/main/include/directx/d3dx12.h)