Add a gotcha for streaming responses

README.md

@@ -199,6 +199,19 @@ Using pnpm:
 pnpm run shopify app config push
 ```
 
+### Using Defer & await for streaming responses
+
+To test defer/await locally you'll need to use the Shopify CLI slightly differently:
+
+1. First setup ngrok: https://ngrok.com/product/secure-tunnels
+2. Create an ngrok tunnel on port 8080: `ngrok http 8080`.
+3. Copy the forwarding address. This should be something like: `https://f355-2607-fea8-bb5c-8700-7972-d2b5-3f2b-94ab.ngrok-free.app`
+4. In a separate terminal run `yarn shopify app dev --tunnel-url=TUNNEL_URL:8080` replacing `TUNNEL_URL` for the address you copied in step 3.
+
+By default the CLI uses a cloudflare tunnel. Unfortunately it looks like cloudflare tunnels wait for the Response stream to finish, then sends one chunk.
+
+This will not affect production, since tunnels are only for local development.
+
 ## Benefits
 
 Shopify apps are built on a variety of Shopify tools to create a great merchant experience.