add: note on using hf datasets.

[sayakpaul]

Hi @dwofk!

Thanks for your great work on open-sourcing this repository.

At Hugging Face, we recently welcomed the NYU Depth V2 dataset (the preprocessed version distributed from this repo). Using the dataset is now as easy as the following:

from datasets import load_dataset # installation is `pip install datasets`

nyu = load_dataset("sayakpaul/nyu_depth_v2")

This PR just adds a note about this.