Have documentation fail on warning (#5189)
Have documentation fail on warning (#5189)

* Have documentation fail on warning

* Force ci failure

* Revert "Force ci failure"

This reverts commit f0a4666ec2eb4cd00a4da48af3357defc63324a0.
huggingface/transformers,huggingface/transformers,huggingface/transformers,huggingface/pytorch-transformers,huggingface/transformers