Create Modelcard for Reformer Model

model_cards/patrickvonplaten/reformer-crime-and-punish/README.md

+## Reformer Model trained on "Crime and Punishment" 
+Crime and Punishment text was taken from `gs://trax-ml/reformer/crime-and-punishment-2554.txt`.
+Model was trained in flax using colab notebook proposed by authors: https://colab.research.google.com/github/google/trax/blob/master/trax/models/reformer/text_generation.ipynb
+Weights were converted to Hugging Face PyTorch `ReformerModelWithLMHead`.