Fixes a typo in loading documentation
{'login': 'sighingnow', 'id': 7144772, 'node_id': 'MDQ6VXNlcjcxNDQ3NzI=', 'avatar_url': 'https://avatars.githubusercontent.com/u/7144772?v=4', 'gravatar_id': '', 'url': 'https://api.github.com/users/sighingnow', 'html_url': 'https://github.com/sighingnow', 'followers_url': 'https://api.github.com/users/sighingnow/followers', 'following_url': 'https://api.github.com/users/sighingnow/following{/other_user}', 'gists_url': 'https://api.github.com/users/sighingnow/gists{/gist_id}', 'starred_url': 'https://api.github.com/users/sighingnow/starred{/owner}{/repo}', 'subscriptions_url': 'https://api.github.com/users/sighingnow/subscriptions', 'organizations_url': 'https://api.github.com/users/sighingnow/orgs', 'repos_url': 'https://api.github.com/users/sighingnow/repos', 'events_url': 'https://api.github.com/users/sighingnow/events{/privacy}', 'received_events_url': 'https://api.github.com/users/sighingnow/received_events', 'type': 'User', 'site_admin': False}
[]
[]
As show in the [documentation page](https://huggingface.co/docs/datasets/loading) here the `"tr"in` should be `"train`.

![image](https://user-images.githubusercontent.com/7144772/188390445-e1f04d54-e3e3-4762-8686-63ecbe4087e5.png)

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