Make trained model available

[jeremyforest]

Down the line we should have all pretrained models available in a folder. That would enable users that work with animal we have a pretrained model of, to not have to do the training step, or only a slight tuning of the model with even fewer annotated images.

[jeremyforest]

Ideally this should be a section in the documentation where we build a zoo of the behavioral paradigms / situations we have trained annolid on.
For example :

• behavioral paradigm 1 (eg open field with an example video or at least some image) --> link to trained model weights
• behavioral paradigm 2 --> trained model weights
• ...