datasets-cli: convertion of a tfds dataset to a huggingface one.
Hi,

the MNIST dataset is already available on the Hub. You can use it as follows:
```python
import datasets
dataset_dict = datasets.load_dataset("mnist")
```

As for the conversion of TFDS datasets to HF datasets, we will be working on it in the coming months, so stay tuned.
### Discussed in https://github.com/huggingface/datasets/discussions/3079

<div type='discussions-op-text'>

<sup>Originally posted by **vitalyshalumov** October 14, 2021</sup>
I'm trying to convert a tfds dataset to a huggingface one.

I've tried:

1.       datasets-cli convert  --tfds_path ~/tensorflow_datasets/mnist/3.0.1/ --datasets_directory ~/.cache/huggingface/datasets/mnist/3.0.1/

2.       datasets-cli convert  --tfds_path ~/tensorflow_datasets/mnist/3.0.1/ --datasets_directory ~/.cache/huggingface/datasets/


and other permutations.
The script appears to be running and finishing without an error but when looking in the  huggingface/datasets/ folder nothing is created.


</div>