Update README.md

Hi there! I wanted to say that your model is fantastic and has been incredibly useful. We are interested in contributing to update the README to include the base_model information. This is to help address the missing details in the model card. Thank you for your great work!

README.md

@@ -14,6 +14,8 @@ metrics:
 - sari
 - bleu
 - accuracy
+base_model:
+- google/flan-t5-large
 widget:
 - text: 'Fix the grammar: When I grow up, I start to understand what he said is quite
     right.'