[BUG] Broken link in TorchAlgo link in example

[ThibaultFy]

Describe the bug

Links are broken in the doc both Torch algorithm in text and when you click on the code on the TorchAlgo class it redirects to ABC

How To Reproduce

Steps to reproduce the behavior:

1. Click here https://docs.substra.org/en/stable/substrafl_doc/examples/get_started/run_mnist_torch.html#sphx-glr-substrafl-doc-examples-get-started-run-mnist-torch-py:~:text=class%20MyAlgo(TorchFedAvgAlgo)%3A

Expected behavior

Redirect to https://docs.python.org/3/library/abc.html#abc.ABC

[KindEmily]

Still not working :c