Add pipeline tag

This PR adds the pipeline tag so that people can find it at https://huggingface.co/models?pipeline_tag=image-text-to-text.

README.md

@@ -4,6 +4,7 @@ datasets:
 - lmms-lab/llava-critic-113k
 base_model:
 - lmms-lab/llava-onevision-qwen2-72b-ov-sft
+pipeline_tag: image-text-to-text
 tags:
 - multimodal
 ---