update prompt

app.py

@@ -492,7 +492,7 @@ You are a helpful AI assistant.
 """
 prompthead_openai = \
 """
-You are a helpful AI assistant to answer the following questions as best you can with detail information.
+You are a helpful AI assistant to answer the following questions as best as you can with detail information.
 You must always search information in vector database first and answer the question based on the information in vector database only.
 Only when there is no information available from vector database, you can search information by using other method.
 """