Librarian Bot: Add base_model information to model

This pull request aims to enrich the metadata of your model by adding [`roberta-base`](https://huggingface.co/roberta-base) as a `base_model` field, situated in the `YAML` block of your model's `README.md`.

How did we find this information? We performed a regular expression match on your `README.md` file to determine the connection.

**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).

If you want to automatically add `base_model` metadata to more of your modes you can use the [Librarian Bot](https://huggingface.co/librarian-bot) [Metadata Request Service](https://huggingface.co/spaces/librarian-bots/metadata_request_service)!

README.md

@@ -1,17 +1,18 @@
 ---
+language:
+- en
+license: apache-2.0
+library_name: span-marker
 tags:
 - token-classification
 - named-enity-recognition
 datasets:
 - DFKI-SLT/few-nerd
+pipeline_tag: token-classification
+base_model: roberta-base
 model-index:
 - name: span-marker-robert-base
   results: []
-license: apache-2.0
-language:
-- en
-library_name: span-marker
-pipeline_tag: token-classification
 ---
 
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