Why the codes of training BERT from scratch are deprecated 
## ❓ Questions & Help
I'm wondering why the team removed the codes of training BERT from scratch, including pregenerate_training_data.py and finetune_on_pregenerated.py. They're very helpful and I still continue developing them to train the BERT as well as Roberta from scratch. 
They were community provided and the core team didn't have the bandwidth to maintain them.

Also we want to limit the number of single-model examples now and favor examples that work for a range of models.

If you want to update them to the current version of the repo and add the various models (for instance all the models currently in `run_lm_finetuning`), happy to review a PR.<|||||>This issue has been automatically marked as stale because it has not had recent activity. It will be closed if no further activity occurs. Thank you for your contributions.
