Add the Sentence Transformers tag

Hello!

This PR adds the Sentence Transformers tags, allowing people to find this model more easily when searching for embedding models under https://huggingface.co/models?library=sentence-transformers&sort=trending

- Tom Aarsen

README.md

@@ -1,6 +1,7 @@
 ---
 tags:
 - mteb
+- sentence-transformers
 model-index:
 - name: NV-Embed-v2
   results: