README: x16 replication is a local prep step, not a hub file

Remove x16 val replication (materialize locally at prep time)

Upload README.md with huggingface_hub

Upload deepscaler_medium_20k_val500_x16.parquet with huggingface_hub

Upload deepscaler_medium_20k_val500.parquet with huggingface_hub

Upload deepscaler_medium_20k_train.parquet with huggingface_hub

initial commit