Some minor errors in the README file

[czzhangheng]

1. In the utils script commands, the last two commands may need to change their "output_dir".

2. After the "train a model" command, the config file path points directly to "configs/p3d.yml", but it should point to "configs/hypertuning/p3d.yml". 3. Before training, you may need to create two folders, "./saved_models" and "./studies/losses". Otherwise you may get the exception "Parent directory ./saved_models does not exist".

I'm learning about traffic flow forecasting. Your code has helped me a lot, thank you! 🌹