Add document describing the HTTP chat protocol (#1193)

* Add protocol md and link

* Remove protocol doc, update links

Author: pamelafox

README.md

@@ -280,6 +280,7 @@ For the frontend code, change `BACKEND_URI` in `api.ts` to point at the deployed
 For an alternate frontend that's written in Web Components and deployed to Static Web Apps, check out
 [azure-search-openai-javascript](https://github.com/Azure-Samples/azure-search-openai-javascript) and its guide
 on [using a different backend](https://github.com/Azure-Samples/azure-search-openai-javascript#using-a-different-backend).
+Both these repositories adhere to the same [HTTP protocol for RAG chat apps](https://github.com/Azure-Samples/ai-chat-app-protocol).
 
 ## Running locally
 

docs/customization.md

@@ -27,7 +27,7 @@ The frontend is built using [React](https://reactjs.org/) and [Fluent UI compone
 
 ## Customizing the backend
 
-The backend is built using [Quart](https://quart.palletsprojects.com/), a Python framework for asynchronous web applications. The backend code is stored in the `app/backend` folder.
+The backend is built using [Quart](https://quart.palletsprojects.com/), a Python framework for asynchronous web applications. The backend code is stored in the `app/backend` folder. The frontend and backend communicate using the [AI Chat App HTTP Protocol](https://github.com/Azure-Samples/ai-chat-app-protocol).
 
 ### Chat/Ask tabs