Update pipeline tag

This PR ensures the model is in the same list as llava, qwen2-vl, llava-onevision, etc: https://huggingface.co/models?pipeline_tag=image-text-to-text&sort=trending.

README.md

@@ -3,6 +3,7 @@ license: apache-2.0
 language:
 - en
 library_name: transformers
+pipeline_tag: image-text-to-text
 tags:
 - multimodal
 - aria