ELI5 no longer available, but referenced in example code

[drdsgvo]

Here, an example code is given:
https://huggingface.co/docs/transformers/tasks/language_modeling

This code + article references the ELI5 dataset.
ELI5 is no longer available, as the ELI5 dataset page states: https://huggingface.co/datasets/eli5
"Defunct: Dataset "eli5" is defunct and no longer accessible due to unavailability of the source data.
Reddit recently changed the terms of access to its API, making the source data for this dataset unavailable.
"

Please change the example code to use a different dataset.

[mariosasko]

Addressed in huggingface/transformers#28715.