Update doc

[leobxpan]

Thanks for the great work. The doc accompanying the code seems to be super outdated. Could you please update the instructions on environment, training / testing, and pre-trained models? That'd be very helpful.

[leobxpan]

model/loss_utils.py seems to be missing too.

[garvita-tiwari]

I have updated the installation file with requirements and also updated the pretrained model. Please check the updated repo.