Typo in GrabNet data setup

old:
python grabnet/data/unzip_data.py   --data-path $PATH_TO_FOLDER_WITH_ZIP_FILES \
                                    --ectract-path $PATH_TO_EXTRACT_DATASET_TO
                                    
new:
python grabnet/data/unzip_data.py   --data-path $PATH_TO_FOLDER_WITH_ZIP_FILES \
                                    --extract-path $PATH_TO_EXTRACT_DATASET_TO                                    