Add base model metadata to model card

It would be nice to trace the genealogy of merged models like this: https://colab.research.google.com/drive/1s2eQlolcI1VGgDhqWIANfkfKvcKrMyNr?usp=sharing

README.md

@@ -7,6 +7,9 @@ language:
 pipeline_tag: text-generation
 tags:
 - Math
+base_model:
+- fblgit/una-cybertron-7b-v2-bf16
+- meta-math/MetaMath-Mistral-7B
 ---
 
 ## MetaMath-Cybertron