minor #13139 Update installation.rst (abdounikarim)

This PR was submitted for the 5.0 branch but it was squashed and merged into the 4.4 branch instead (closes #13139).

Discussion
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Update installation.rst

Hello,

I just updated the code using the last known configuration in Symfony Recipes for Webpack Encore Bundle 😉

Commits
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c37b446 Update installation.rst

Author: javiereguiluz

frontend/encore/installation.rst

@@ -55,6 +55,13 @@ is the main config file for both Webpack and Webpack Encore:
 .. code-block:: javascript
 
     var Encore = require('@symfony/webpack-encore');
+    
+    // Manually configure the runtime environment if not already configured yet by the "encore" command.
+    // It's useful when you use tools that rely on webpack.config.js file.
+    
+    if (!Encore.isRuntimeEnvironmentConfigured()) {
+        Encore.configureRuntimeEnvironment(process.env.NODE_ENV || 'dev');
+    }
 
     Encore
         // directory where compiled assets will be stored
@@ -76,24 +83,49 @@ is the main config file for both Webpack and Webpack Encore:
         .addEntry('app', './assets/js/app.js')
         //.addEntry('page1', './assets/js/page1.js')
         //.addEntry('page2', './assets/js/page2.js')
+        
+        // When enabled, Webpack "splits" your files into smaller pieces for greater optimization.
+        .splitEntryChunks()
 
         // will require an extra script tag for runtime.js
         // but, you probably want this, unless you're building a single-page app
         .enableSingleRuntimeChunk()
 
+        /*
+         * FEATURE CONFIG
+         *
+         * Enable & configure other features below. For a full
+         * list of features, see:
+         * https://symfony.com/doc/current/frontend.html#adding-more-features
+         */
         .cleanupOutputBeforeBuild()
+        .enableBuildNotifications()
         .enableSourceMaps(!Encore.isProduction())
         // enables hashed filenames (e.g. app.abc123.css)
         .enableVersioning(Encore.isProduction())
+        
+        // enables @babel/preset-env polyfills
+        .configureBabelPresetEnv((config) => {
+            config.useBuiltIns = 'usage';
+            config.corejs = 3;
+        })
+        
+        // enables Sass/SCSS support
+        //.enableSassLoader()
 
         // uncomment if you use TypeScript
         //.enableTypeScriptLoader()
-
-        // uncomment if you use Sass/SCSS files
-        //.enableSassLoader()
+        
+        // uncomment to get integrity="..." attributes on your script & link tags
+        // requires WebpackEncoreBundle 1.4 or higher
+        //.enableIntegrityHashes(Encore.isProduction())
 
         // uncomment if you're having problems with a jQuery plugin
         //.autoProvidejQuery()
+        
+        // uncomment if you use API Platform Admin (composer require api-admin)
+        //.enableReactPreset()
+        //.addEntry('admin', './assets/js/admin.js')
     ;
 
     module.exports = Encore.getWebpackConfig();
@@ -107,7 +139,7 @@ import some CSS:
 
     require('../css/app.css');
 
-    console.log('Hello Webpack Encore');
+    console.log('Hello Webpack Encore! Edit me in assets/js/app.js');
 
 And the new ``assets/css/app.css`` file: