Wrong names in README for training Standard PGD AT

[headscott]

Shouldn't all of the Standard PGD AT make commands contain PGDAR_RaResNet50 as the name?

Because, I had to do resize.py (step 4 of the other github which is mentioned in your step 1 of GetStarted) although I did not want to run Fast AT. After I finished, I found out that the command mentioned probably is probably just wrong, so I did not have to do resize.py, but just run make experiments/PGDAT_RaResNet50/.done_train instead of make experiments/RaResNet50/.done_train