docs(langchain): correct import paths in agent middleware docstrings (#36987)

Author: bansalkanav

libs/langchain_v1/langchain/agents/middleware/model_fallback.py

@@ -29,7 +29,7 @@ class ModelFallbackMiddleware(AgentMiddleware[AgentState[ResponseT], ContextT, R
 
     Example:
         ```python
-        from langchain.agents.middleware.model_fallback import ModelFallbackMiddleware
+        from langchain.agents.middleware import ModelFallbackMiddleware
         from langchain.agents import create_agent
 
         fallback = ModelFallbackMiddleware(

libs/langchain_v1/langchain/agents/middleware/todo.py

@@ -174,7 +174,7 @@ class TodoListMiddleware(AgentMiddleware[PlanningState[ResponseT], ContextT, Res
 
     Example:
         ```python
-        from langchain.agents.middleware.todo import TodoListMiddleware
+        from langchain.agents.middleware import TodoListMiddleware
         from langchain.agents import create_agent
 
         agent = create_agent("openai:gpt-4o", middleware=[TodoListMiddleware()])