Fix dead link (#3453)

Fix another dead link

packages/react-scripts/config/jest/cssTransform.js

@@ -9,7 +9,7 @@
 'use strict';
 
 // This is a custom Jest transformer turning style imports into empty objects.
-// http://facebook.github.io/jest/docs/tutorial-webpack.html
+// http://facebook.github.io/jest/docs/en/webpack.html
 
 module.exports = {
   process() {

packages/react-scripts/config/jest/fileTransform.js

@@ -11,7 +11,7 @@
 const path = require('path');
 
 // This is a custom Jest transformer turning file imports into filenames.
-// http://facebook.github.io/jest/docs/tutorial-webpack.html
+// http://facebook.github.io/jest/docs/en/webpack.html
 
 module.exports = {
   process(src, filename) {