Add nginx readme

Author: adaam2

README.md

@@ -70,6 +70,8 @@ The application can be built using `docker-compose up --build`.
 
 There are several interlinking services orchestrated in individual containers: `db` (the postgresql instance), `backend` (the Rails api), `frontend` (the React application) and finally the `nginx` proxy container which pulls everything together and which is the only container which exposes any ports to the host machine.
 
+The nginx conf can be found at `/config/nginx/nginx.conf`.
+
 The Rails application is proxied from port `3000` to `http://localhost:8080/api` and the Webpack / React application is proxied from port `4000` to the root at `http://localhost:8080/`.
 
 The React application was originally created using `create-react-app` but was ejected to expose the full configuration.