message: Add PyTorch hint to README
diff: @@ -41,3 +41,9 @@ The `autofl` package contains the following sub-packages:
  - [Communication-Efficient Learning of Deep Networks from Decentralized Data](https://arxiv.org/abs/1602.05629)
  - [Analyzing Federated Learning through an Adversarial Lens](https://arxiv.org/abs/1811.12470)
  - [Towards Federated Learning at Scale: System Design](https://arxiv.org/abs/1902.01046)
  +
  +## PyTorch
  +
  +PyTorch might require the following native library on macOS:
  +
  +`brew install libomp`
  