Fix Syntax Error

Add the comma which has been annotated

README.md

@@ -57,7 +57,7 @@ pipe = DiffusionPipeline.from_pretrained(model_name, torch_dtype=torch_dtype)
 pipe = pipe.to(device)
 
 positive_magic = {
-    "en": "Ultra HD, 4K, cinematic composition." # for english prompt,
+    "en": "Ultra HD, 4K, cinematic composition.", # for english prompt,
     "zh": "超清，4K，电影级构图" # for chinese prompt,
 }