Document ResNet architecture tweak

[NicolasHug]

Since we're revamping our docs, we might want to point out that our ResNet implementation slightly differs from the original one:

https://github.com/pytorch/vision/blob/970ba3555794d163daca0ab95240d21e3035c304/torchvision/models/resnet.py#L107:L111

We have this as a comment in the code but it's worth documenting in the docs as well as .. note:: IMHO

[datumbox]

Another good example of a post-paper optimization adopted in the code-base. I agree we should document this clearly on our new documentation. I was thinking that perhaps the best place to put the note is at the ResNet doc. What do you think @NicolasHug?

[NicolasHug]

I agree we should add it to the main resnet page. But because some users might land directly on one of the builder's page without going from the main Resnet one, I feel like we should also document this in the docstrings. Either by duplicating the same text, or perhaps by just adding a reference to the .. note.

[datumbox]

Sounds good to me.

[puhuk]

Can I send PR with this?
If so, should I send another PR for docstring? (https://pytorch.org/vision/main/models/generated/torchvision.models.resnet18.html#torchvision.models.resnet18)

[NicolasHug]

@puhuk sure, thanks! I think we should be able to tackle all this in a single PR