Add root parameter to training script. Use --dataset.root_dir to set root dir#690

rkeshwani wants to merge 2 commits intohuggingface:mainhuggingface/lerobot:mainfrom

rkeshwani:689-missing-root-param-in-training-scriptrkeshwani/lerobot:689-missing-root-param-in-training-scriptCopy head branch name to clipboard