Unifiy prompt params

Signed-off-by: junjie.jiang <junjie.jiang@zilliz.com>

README.md

@@ -33,9 +33,9 @@ p = (
     .output('answer')
 )
 
-an1 = p('Tell me something about Towhee', [towhee_docs], []).get()[0]
+an1 = p('Tell me something about Towhee', towhee_docs, []).get()[0]
 
-an2 = p('Give an example', [towhee_docs], [('Tell me something about Towhee', an1)]).get()[0]
+an2 = p('Give an example', towhee_docs, [('Tell me something about Towhee', an1)]).get()[0]
 
 ```
 

qa_prompt.py

@@ -38,12 +38,11 @@ class QAPrompt(PyOperator):
                 logger.warning('Unkown llm_name, use default prompt')
                 self._template = gpt_prompt
 
-    def __call__(self, question: str, docs: List[str], history=Optional[List[Tuple]]) -> List[Dict[str, str]]:
+    def __call__(self, question: str, context: str, history=Optional[List[Tuple]]) -> List[Dict[str, str]]:
         """
         history:
             List[Tuple]: [(question1, answer1), (question2, answer2)]
         """
-        context = '\n'.join(docs)
         prompt_str = self._template.format(context=context, question=question)
         ret = [{'question': prompt_str}]
         if not isinstance(history, list):