Librarian Bot: Add base_model metadata to model

This pull request aims to enrich the metadata of your model by adding `base_model` metadata to `YAML` block of your model's `README.md`.

How did we find this information? We use the `mergekit_config.yml` config from [mergekit](https://github.com/cg123/mergekit).

**Why add this?** Enhancing your model's metadata in this way:
- **Boosts Discoverability** - It becomes straightforward to trace the relationships between various models on the Hugging Face Hub.
- **Highlights Impact** - It showcases the contributions and influences different models have within the community.

For a hands-on example of how such metadata can play a pivotal role in mapping model connections, take a look at [librarian-bots/base_model_explorer](https://huggingface.co./spaces/librarian-bots/base_model_explorer).

This PR comes courtesy of [Librarian Bot](https://huggingface.co./librarian-bot). If you have any feedback, queries, or need assistance, please don't hesitate to reach out to [@davanstrien](https://huggingface.co./davanstrien).

README.md

@@ -6,6 +6,9 @@ tags:
 - wanglab/ClinicalCamel-70B
 - epfl-llm/meditron-70b
 - allenai/tulu-2-dpo-70b
+base_model:
+- NousResearch/Llama-2-70b-hf
+- allenai/tulu-2-dpo-70b
 ---
 
 # Medmerge-tulu-70b