Duplicate CLI file warning header

packages/create-react-app/createReactApp.js

@@ -6,6 +6,34 @@
  * LICENSE file in the root directory of this source tree. An additional grant
  * of patent rights can be found in the PATENTS file in the same directory.
  */
+
+// ~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~
+//   /!\ DO NOT MODIFY THIS FILE /!\
+// ~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~
+//
+// create-react-app is installed globally on people's computers. This means
+// that it is extremely difficult to have them upgrade the version and
+// because there's only one global version installed, it is very prone to
+// breaking changes.
+//
+// The only job of create-react-app is to init the repository and then
+// forward all the commands to the local version of create-react-app.
+//
+// If you need to add a new command, please add it to the scripts/ folder.
+//
+// The only reason to modify this file is to add more warnings and
+// troubleshooting information for the `create-react-app` command.
+//
+// Do not make breaking changes! We absolutely don't want to have to
+// tell people to update their global version of create-react-app.
+//
+// Also be careful with new language features.
+// This file must work on Node 4+.
+//
+// ~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~
+//   /!\ DO NOT MODIFY THIS FILE /!\
+// ~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~
+
 'use strict';
 
 const validateProjectName = require('validate-npm-package-name');