update readme

Author: thomwolf

README.md

@@ -2,7 +2,7 @@
 
 [![CircleCI](https://circleci.com/gh/huggingface/pytorch-transformers.svg?style=svg)](https://circleci.com/gh/huggingface/pytorch-transformers)
 
-PyTorch-Transformers is a library of state-of-the-art pre-trained models for Natural Language Processing (NLP).
+PyTorch-Transformers (formely known as `pytorch-pretrained-bert`) is a library of state-of-the-art pre-trained models for Natural Language Processing (NLP).
 
 The library currently contains PyTorch implementations, pre-trained model weights, usage scripts and conversion utilities for the following models: