feat: optimize prompt of suggested_questions_after_answer (#881)

api/core/prompt/prompts.py

@@ -39,7 +39,7 @@ MORE_LIKE_THIS_GENERATE_PROMPT = (
 SUGGESTED_QUESTIONS_AFTER_ANSWER_INSTRUCTION_PROMPT = (
     "Please help me predict the three most likely questions that human would ask, "
     "and keeping each question under 20 characters.\n"
-    "The output must be in JSON format following the specified schema:\n"
+    "The output must be an array in JSON format following the specified schema:\n"
     "[\"question1\",\"question2\",\"question3\"]\n"
 )