Correct conversation history tutorial example (#9071)

Author: zhiyanliu

docs/docs/tutorials/conversation_history/index.md

@@ -195,15 +195,15 @@ The capital of France is Paris.
 User message:
 
 [[ ## question ## ]]
-What is the capital of Germany?
+What is the capital of America?
 
 Respond with the corresponding output fields, starting with the field `[[ ## answer ## ]]`, and then ending with the marker for `[[ ## completed ## ]]`.
 
 
 Response:
 
 [[ ## answer ## ]]
-The capital of Germany is Berlin.
+The capital of the United States of America is Washington, D.C.
 
 [[ ## completed ## ]]
 ```