fix elastic rag template in playground (#12682)

- a few instructions in the readme (load_documents -> ingest.py)
- added docker run command for local elastic
- adds input type definition to render playground properly

templates/chat-bot-feedback/chat_bot_feedback/chain.py

@@ -165,7 +165,6 @@ def format_chat_history(chain_input: dict) -> dict:
 # with the new `tool.langserve.export_attr`
 chain = (
     (format_chat_history | _prompt | _model | StrOutputParser())
-    .with_types(input_type=ChainInput)
     # This is to add the evaluators as "listeners"
     # and to customize the name of the chain.
     # Any chain that accepts a compatible input type works here.
@@ -180,3 +179,5 @@ chain = (
         ],
     )
 )
+
+chain = chain.with_types(input_type=ChainInput)