Upload README via `push_to_hub`
You can use `huggingface_hub`'s [Card API](https://huggingface.co/docs/huggingface_hub/package_reference/cards) to programmatically push a dataset card to the Hub.
### Feature request

`push_to_hub` now allows users to upload datasets programmatically. However, based on the latest doc, we still need to open the dataset page to add readme file manually.

However, I do discover snippets to intialize a README for every `push_to_hub`:
```
dataset_card = (
    DatasetCard(
        "---\n"
        + str(dataset_card_data)
        + "\n---\n"
        + f'# Dataset Card for "{repo_id.split("/")[-1]}"\n\n[More Information needed](https://github.com/huggingface/datasets/blob/main/CONTRIBUTING.md#how-to-contribute-to-the-dataset-cards)'
    )
    if dataset_card is None
    else dataset_card
)

HfApi(endpoint=config.HF_ENDPOINT).upload_file(
    path_or_fileobj=str(dataset_card).encode(),
    path_in_repo="README.md",
    repo_id=repo_id,
    token=token,
    repo_type="dataset",
    revision=branch,
)
```

So, if we can enable `push_to_hub` to upload a readme file by ourselves instead of using the auto generated ones, it can save ton of time, and will definitely alleviate the current "lack-of-dataset-card" situation.

### Motivation

as elabrated above.

### Your contribution

I might be able to make a pr.