Docs: Why not all models are in the docs?

[luizamfsantos]

I was following this tutorial: https://pytorch-geometric.readthedocs.io/en/latest/tutorial/graph_transformer.html

And I couldn't find anywhere in the docs about the PerformerAttention from https://github.com/pyg-team/pytorch_geometric/blob/master/torch_geometric/nn/attention/performer.py#L98

I thought it should be here: https://pytorch-geometric.readthedocs.io/en/latest/modules/nn.html

[xnuohz]

plz check https://pytorch-geometric--10089.org.readthedocs.build/en/10089/modules/nn.html#attention before #10089 is merged