Short for DirectX Research layer. The project is intended to help it's creator with research of modern graphics algorithms and technologies, it is not a rendering engine, though it has some similarities.
DirectX 12 was taken as a foundation for the DX Research Layer. It is complex a bit to start with, but author believes modern "next-gen" graphics API is the best choice for further applications.
Unfortunately, author haven't yet formed a complex view on how DXRL should be structured, many changes are to come, so author believes it's not the best time for any solid tutorial.