GitLab

Summary:
Added readme for IMDB classification as tutorial for custm finetuning of roberta
Pull Request resolved: https://github.com/fairinternal/fairseq-py/pull/790

Reviewed By: myleott

Differential Revision: D16587877

Pulled By: myleott

fbshipit-source-id: ed265b7254e6fa2fc8a899ba04c0d2bb45a7f5c4