Set a rule on the config and split names
in this case we need to decide what to do with the existing datasets with white space characters (there shouldn't be a lot of them I think) I imagine that we should stop supporting them, and help the user fix them?
> should we actually allow characters like spaces? maybe it's better to add validation for whitespace symbols and directly in datasets and raise

https://github.com/huggingface/datasets-server/issues/853
