Arxiv README (#2747)

* Arxiv README

* ArXiv-NLP readme

model_cards/lysandre/arxiv/README.md

@@ -0,0 +1,7 @@
+# ArXiv GPT-2 checkpoint
+
+This is a GPT-2 small checkpoint for PyTorch. It is the official `gpt2-small` finetuned to ArXiv paper on physics fields.
+
+## Training data
+
+This model was trained on a subset of ArXiv papers that were parsed from PDF to txt. The resulting data is made of 130MB of text, mostly from quantum physics (quant-ph) and other physics sub-fields.