Add "load pytorch tensor" section into the burn book

[med1844]

Issue based on discussion #2315, @antimora

To my best knowledge, here's how to load a tensor:

1. In python: Ensure you wrap the tensor with dict before save, e.g.

   torch.save({"some_key": tensor}, "path/to/tensor.pt")

2. In rust:

   #[derive(Module, Debug)]
   struct FloatTensor<B: Backend, const D: usize> {
       some_key: Param<Tensor<B, D>>,
   }
   
   fn main() {
       type B = NdArray;
       let device = Default::default();
       let tensor: FloatTensorRecord<B, 3> =
           PyTorchFileRecorder::<FullPrecisionSettings>::new()
               .load("path/to/tensor.pt".into(), &device)
               .unwrap();
       let tensor = tensor.value.val();
   }

[csking101]

Hi, could I take up this issue?

[antimora]

Hi, could I take up this issue?

Yes! Please go ahead. We would appreciate your contribution. Let me know if you need more info.