Add more precise license metadata (UI will be cleaner!)

Part of hacktoberfest_challenge -> [Hugging Face hub-docs] (https://github.com/huggingface/hub-docs/blob/main/hacktoberfest_challenges/model_license_other.md)

README.md

@@ -2,7 +2,7 @@
 inference: false
 language:
 - en
-license: other
+license: llama2
 model_type: llama
 pipeline_tag: text-generation
 tags: