Migrate model card from transformers-repo

Read announcement at https://discuss.huggingface.co/t/announcement-all-model-cards-will-be-migrated-to-hf-co-model-repos/2755
Original file history: https://github.com/huggingface/transformers/commits/master/model_cards/akhooli/xlm-r-large-arabic-toxic/README.md

README.md

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+---
+
+language:
+- ar
+- en
+
+license: mit
+---
+### xlm-r-large-arabic-toxic (toxic/hate speech classifier) 
+Toxic (hate speech) classification (Label_0: non-toxic, Label_1: toxic) of Arabic comments by fine-tuning XLM-Roberta-Large. 
+Zero shot classification of other languages (also works in mixed languages - ex. Arabic & English).  
+Usage and further info: see last section in this [Colab notebook](https://lnkd.in/d3bCFyZ)