Update demo.py in README (#458)

* Update demo.py in README

* Update README.md

README.md

@@ -41,10 +41,22 @@ import chainlit as cl
 
 @cl.on_message  # this function will be called every time a user inputs a message in the UI
 async def main(message: str):
-    # this is an intermediate step
-    await cl.Message(author="Tool 1", content=f"Response from tool1", indent=1).send()
+    """
+    This function is called every time a user inputs a message in the UI.
+    It sends back an intermediate response from Tool 1, followed by the final answer.
 
-    # send back the final answer
+    Args:
+        message: The user's message.
+
+    Returns:
+        None.
+    """
+
+    # Send an intermediate response from Tool 1.
+    await cl.Message(
+        author="Tool 1", content=f"Response from tool1", indent=1).send()
+
+    # Send the final answer.
     await cl.Message(content=f"This is the final answer").send()
 ```