Add dataset info headline.

Informing the user that the model works best on natural scenes as Places365 consists of images diverse natural landscapes.

app.py

@@ -145,7 +145,7 @@ HEAD = """
 """
 
 with gr.Blocks(theme=THEME, title="Image Colorizer", head=HEAD) as demo:
-    gr.Markdown("# 🎨 Image Colorizer")
+    gr.Markdown("# 🎨 Image Colorizer\nWorks best on natural scenes. Learn more about the dataset we trained on [here.](http://places.csail.mit.edu/)")
     
     result_state = gr.State()