Add note about presets

Author: driesvints

README.md

@@ -8,6 +8,8 @@
 
 While Laravel does not dictate which JavaScript or CSS pre-processors you use, it does provide a basic starting point using [Bootstrap](https://getbootstrap.com/) and [Vue](https://vuejs.org/) that will be helpful for many applications. By default, Laravel uses [NPM](https://www.npmjs.org/) to install both of these frontend packages.
 
+**We are not accepting new presets.**
+
 ## Official Documentation
 
 Documentation can be found on the [Laravel website](https://laravel.com/docs/frontend).