Adding the HAREM dataset
Thanks for the changes !

Sorry if I wasn't clear about the suggestion of adding the `raw` dataset as well.
By `raw` I meant the dataset with its original features, i.e. not tokenized to follow the conll format for NER.
The `raw` dataset has data fields `doc_text`, `doc_id` and `entities`. Alright, @lhoestq, now I understand your suggestion, but the JSON files the script downloads aren't actually the "raw" HAREM dataset, the [real raw version](https://www.linguateca.pt/primeiroHAREM/harem/ColeccaoDouradaHAREM.zip) of it is on XML format that needs a lot of preprocessing. Those JSON are just pre-processed versions of the dataset.

I can make the config of the raw version of the pre-processed dataset, but I'll leave a comment on the dataset summary about those details. Oh I see ! Sorry I thought there really were the raw (i.e. original/unprocessed) files The original xml format doesn't seem very practical to use :/ 
We can ignore that and only keep the default and selective configs then.
Can you revert to the old configs ?

Thanks again for adding this dataset ! Hi @lhoestq, I've reverted the changes and put more details on README about the dataset.
Adding the HAREM dataset, a Portuguese language dataset for NER tasks