修改关联提问提示文本为中文，同时增加上提问内容现定于知识库现有内容的要求。

backend/app/api/services/suggestion.py

@@ -6,10 +6,10 @@ from llama_index.core.settings import Settings
 from pydantic import BaseModel
 
 NEXT_QUESTIONS_SUGGESTION_PROMPT = PromptTemplate(
-    "You're a helpful assistant! Your task is to suggest the next question that user might ask. "
+    "你是一个乐于助人的助手！你的任务是对用户可能会问的下一个问题给出建议。 "
-    "\nHere is the conversation history"
+    "\n这是对话历史记录"
     "\n---------------------\n{conversation}\n---------------------"
-    "Given the conversation history, please give me $number_of_questions questions that you might ask next!"
+    "考虑到对话历史记录，仅限于现在知识库已有内容, 请给我 $number_of_questions 个你接下来可能会问题的问题！"
 )
 N_QUESTION_TO_GENERATE = 3