Add `library_name` to metadata

This PR adds the `library_name: transformers` metadata tag to the model card. This will enable the automated "How to Use" code snippet on the Hugging Face Hub, improving discoverability and ease of use for the model. The model's `config.json` indicates compatibility with the Transformers library.

README.md

@@ -1,13 +1,15 @@
 ---
-license: apache-2.0
 datasets:
 - databricks/databricks-dolly-15k
 language:
 - en
+license: apache-2.0
 metrics:
 - rouge
 pipeline_tag: text-generation
+library_name: transformers
 ---
+
 # MiniLLM-Llama-7B
 
 [paper](https://arxiv.org/abs/2306.08543) | [code](https://github.com/microsoft/LMOps/tree/main/minillm)