Archive pre-trained models and fix README

[rtroncy]

The README mentions that a set of pre-trained models (without further details) are available at https://www.dropbox.com/sh/sc0ffz1sig3ii5b/AAAWlM4DMpWMy2MN3CGKbWjwa?dl=0 while this dropbox link is no longer valid.

We should archive the pre-trained models on Zenodo and fix the README in detailing what pre-trained models exist and linking them to Zenodo.