Update README.md

See ember-cli/ember-cli#2903

README.md

@@ -62,6 +62,8 @@ $ PORT=8000 node server.js
 This will start an HTTP server on port 8000. To stop the server, type
 `Ctrl-C`.
 
+NOTE: If you want to continue running `ember serve` in development, name the file `fastboot-server.js` instead.
+
 ## Application Builds
 
 When you build an Ember.js app via `ember build`, it will build the app
@@ -242,4 +244,4 @@ let server = new FastBootAppServer({
 
 ### Twitter and LinkedIn
 
-As of 2019-06-06, Twitter and LinkedIn's scrapers have a hard time extracting your site's metadata for sharing if `chunkedResponse` is set to `true` in your `server.js` file. Set `chunkedResponse: false` if your meta tags are in place but the [Twitter card validator](https://cards-dev.twitter.com/validator) shows "Card not found" or [LinkedIn's Post Inspector](https://www.linkedin.com/post-inspector/) shows a 500 error.
+As of 2019-06-06, Twitter and LinkedIn's scrapers have a hard time extracting your site's metadata for sharing if `chunkedResponse` is set to `true` in your `server.js` file. Set `chunkedResponse: false` if your meta tags are in place but the [Twitter card validator](https://cards-dev.twitter.com/validator) shows "Card not found" or [LinkedIn's Post Inspector](https://www.linkedin.com/post-inspector/) shows a 500 error.