Read on https://blog.dialogflow.com/post/apiai-new-name-dialogflow-new-features/
Also check out an awesome course on Udemy https://www.udemy.com/chatbots/ by Jana Bergant.
Course “ChatBots: Messenger ChatBot with API.AI and Node.JS” Use API.AI to train chatbot to answer questions and have dialogs. Master API.AI. Create chatbot for Messenger.