Migrate model card from transformers-repo

Read announcement at /static-proxy?url=https%3A%2F%2Fdiscuss.huggingface.co%2Ft%2Fannouncement-all-model-cards-will-be-migrated-to-hf-co-model-repos%2F2755%3Cbr%2F%3EOriginal file history: https://github.com/huggingface/transformers/commits/master/model_cards/facebook/bart-large-cnn/README.md

README.md

@@ -0,0 +1,7 @@
+---
+tags:
+- summarization
+
+license: mit
+thumbnail: https://huggingface.co/front/thumbnails/facebook.png
+---