Rename The Pile subsets
{'login': 'lhoestq', 'id': 42851186, 'node_id': 'MDQ6VXNlcjQyODUxMTg2', 'avatar_url': 'https://avatars.githubusercontent.com/u/42851186?v=4', 'gravatar_id': '', 'url': 'https://api.github.com/users/lhoestq', 'html_url': 'https://github.com/lhoestq', 'followers_url': 'https://api.github.com/users/lhoestq/followers', 'following_url': 'https://api.github.com/users/lhoestq/following{/other_user}', 'gists_url': 'https://api.github.com/users/lhoestq/gists{/gist_id}', 'starred_url': 'https://api.github.com/users/lhoestq/starred{/owner}{/repo}', 'subscriptions_url': 'https://api.github.com/users/lhoestq/subscriptions', 'organizations_url': 'https://api.github.com/users/lhoestq/orgs', 'repos_url': 'https://api.github.com/users/lhoestq/repos', 'events_url': 'https://api.github.com/users/lhoestq/events{/privacy}', 'received_events_url': 'https://api.github.com/users/lhoestq/received_events', 'type': 'User', 'site_admin': False}
[]
[]
Sounds good. Should we also have a “the_pile” dataset with the subsets as configuration? I think the main `the_pile` datasets will be the one that is the mix of all the subsets: https://the-eye.eu/public/AI/pile/

We can also add configurations for each subset, and even allow users to specify the subsets they want:
```python
from datasets import load_dataset

load_dataset("the_pile", subsets=["openwebtext2", "books3", "hn"])
```

We're alrady doing something similar for mC4, where users can specify the list of languages they want to load.
After discussing with @yjernite we think it's better to have the subsets of The Pile explicitly have "the_pile" in their names.

I'm doing the changes for the subsets that @richarddwang added:
- [x] books3 -> the_pile_books3 https://github.com/huggingface/datasets/pull/2801
- [x] stack_exchange -> the_pile_stack_exchange https://github.com/huggingface/datasets/pull/2803
- [x] openwebtext2 -> the_pile_openwebtext2 https://github.com/huggingface/datasets/pull/2802

For consistency we should also rename `bookcorpusopen` to `the_pile_bookcorpus` IMO, but let me know what you think.
(we can just add a deprecation message to `bookcorpusopen` for now and add `the_pile_bookcorpus`)
{'url': 'https://api.github.com/repos/huggingface/datasets/issues/2817/reactions', 'total_count': 0, '+1': 0, '-1': 0, 'laugh': 0, 'hooray': 0, 'confused': 0, 'heart': 0, 'rocket': 0, 'eyes': 0}
{'url': 'https://api.github.com/repos/huggingface/datasets/pulls/2817', 'html_url': 'https://github.com/huggingface/datasets/pull/2817', 'diff_url': 'https://github.com/huggingface/datasets/pull/2817.diff', 'patch_url': 'https://github.com/huggingface/datasets/pull/2817.patch', 'merged_at': '2021-08-23T16:24:09Z'}