Update README.md

[albertter]

Add single-stage pose machines. It's paper proposes a novel Structured Pose Representation (SPR). I think this work is intresting.

[SAtacker]

Also https://interestingengineering.com/facebooks-new-ai-tool-transforms-2d-image-to-3d-models
https://arxiv.org/pdf/2004.00452.pdf --- PIFuHD: Multi-Level Pixel-Aligned Implicit Function for
High-Resolution 3D Human Digitization∗
git https://github.com/facebookresearch/pifuhd