fix error

app.py

@@ -133,7 +133,7 @@ def build_pairwise_browser_tab():
 
 
 def load_demo():
-    dropdown_update = gr.Dropdown.update(value="gpt-4o-mini's battles")
+    dropdown_update = gr.Dropdown.update(value=list(category_selector_map.keys())[0])
     return dropdown_update
 
 
@@ -146,8 +146,8 @@ def build_demo():
     ) as demo:
         gr.Markdown(
             """
-# Chatbot Arena Samples
-We randomly sample 20 battles from each category using seed 42.
+# GPT-4o-Mini Battles
+We randomly sample 1000 battles containing gpt-4o-mini using seed 42.
 | [Paper](https://arxiv.org/abs/2403.04132) | [Leaderboard](https://huggingface.co/spaces/lmsys/chatbot-arena-leaderboard) |
 """
         )