improve custom prompt by specifying "Attached files can be downloaded via the Internet."

app.py

@@ -31,6 +31,8 @@ CUSTOM_PROMPT = """
     - If the answer is a string, do not use articles (a, an, the) or abbreviations.
     - If the answer is a list, apply these rules to each element 
         and separete them with a comma like "a, b, c".
+
+    Attached files can be downloaded via the Internet.
 """
 
 rate_limiter = RateLimiter()