Improve model card: Add GitHub link and relevant tags

This PR enhances the model card by:
- Adding a direct link to the associated GitHub repository (`https://github.com/Nicolas-BZRD/EuroBERT`) in the "Overview" section.
- Improving discoverability by adding more specific tags to the metadata, including `encoder`, `mlm`, `clm`, and `biphasic`, which accurately reflect the core research areas of the model presented in the paper.

These updates make it easier for users to find the code, understand the model's key characteristics, and improve its visibility on the Hugging Face Hub.

README.md

@@ -1,7 +1,12 @@
 ---
-pipeline_tag: feature-extraction
 library_name: transformers
 license: apache-2.0
+pipeline_tag: feature-extraction
+tags:
+  - encoder
+  - mlm
+  - clm
+  - biphasic
 ---
 
 # Overview
@@ -11,6 +16,7 @@ This repository contains an encoder model, part of the research presented in the
 *   **Paper:** [Should We Still Pretrain Encoders with Masked Language Modeling?](https://huggingface.co/papers/2507.00994)
 *   **Blog post:** [Link](https://huggingface.co/blog/Nicolas-BZRD/encoders-should-not-be-only-pre-trained-with-mlm)
 *   **Project page:** [https://hf.co/MLMvsCLM](https://hf.co/MLMvsCLM)
+*   **Code:** [https://github.com/Nicolas-BZRD/EuroBERT](https://github.com/Nicolas-BZRD/EuroBERT)
 
 ## Model Naming