feat(core): Support RAG chat flow (#1185)

docs/docs/awel/cookbook/quickstart_basic_awel_workflow.md

@@ -4,7 +4,7 @@
 
 At first, install dbgpt, and necessary dependencies:
 
-```python
+```shell
 pip install dbgpt --upgrade
 pip install openai
 ```
@@ -14,7 +14,7 @@ Create a python file `simple_sdk_llm_example_dag.py` and write the following con
 ```python
 from dbgpt.core import BaseOutputParser
 from dbgpt.core.awel import DAG
-from dbgpt.core.operator import (
+from dbgpt.core.operators import (
     PromptBuilderOperator,
     RequestBuilderOperator,
 )