add agent id for .env.sample

Signed-off-by: yuye-aws <[email protected]>

Author: yuye-aws

.env.sample

@@ -18,6 +18,7 @@ API_PROVIDER=olly_chat
 # Agents, required if API_PROVIDER is agent_framework
 ROOT_AGENT_ID=
 PPL_AGENT_ID=
+SEARCH_INDEX_AGENT_ID=
 
 # Evaluation models, required if LLM or embeddings based test evaluations are used. fallbacks to reading `.chat-assistant-config` if not provided 
 # ml-commons model id for LLM based requests