Got wrong row number of dataset viewer

Note that .push_to_hub(Main classes) does all the job: upload the Dataset object to a repository on the Hub, in Parquet files, and it prepares the README.md file accordingly.

For dataset-info.json and state.json, and more generally on the recommended way to prepare your dataset, I’ll let @lhoestq or @albertvillanova answer, as I’m not an expert.