Refine prompt_template_source: lmms-eval/VLMEvalKit canonical citations

metadata.json

@@ -44,8 +44,9 @@
         }
       },
       "prompt_template_source": {
-        "origin": "fallback",
-        "reference": "T5"
+        "origin": "official",
+        "reference": "https://github.com/open-compass/VLMEvalKit/blob/main/vlmeval/dataset/image_caption.py (ImageCaptionDataset canonical caption prompt)",
+        "notes": "VLMEvalKit ImageCaptionDataset canonical TextCaps captioning prompt."
       }
     }
   }