Add `library_name: transformers` to metadata

This PR improves the model card by adding `library_name: transformers` to the metadata. This is based on evidence from the `config.json` file (model type, architectures, transformers version) and `tokenizer_config.json` (tokenizer class), confirming compatibility with the Hugging Face Transformers library. Adding this tag will enable the automated "How to use" widget on the model page, making it easier for users to get started with the model.

The existing arXiv paper link has been kept as per guidelines.

README.md

@@ -1,15 +1,17 @@
 ---
-license: apache-2.0
+base_model:
+- facebook/opt-2.7B
 datasets:
 - databricks/databricks-dolly-15k
 language:
 - en
+license: apache-2.0
 metrics:
 - rouge
-base_model:
-- facebook/opt-2.7B
 pipeline_tag: text-generation
+library_name: transformers
 ---
+
 # init-OPT-2.7B
 
 [paper](https://arxiv.org/abs/2306.08543) | [code](https://github.com/microsoft/LMOps/tree/main/minillm)