Merge branch '4.4' into 5.0

* 4.4:
  Update copy-files.rst

Author: OskarStark

frontend/encore/copy-files.rst

@@ -18,7 +18,7 @@ To reference an image tag from inside a JavaScript file, *require* the file:
     // path is relative to this file - e.g. assets/images/logo.png
     const logoPath = require('../images/logo.png');
 
-    var html = `<img src="${logoPath}">`;
+    let html = `<img src="${logoPath}" alt="ACME logo">`;
 
 When you ``require`` (or ``import``) an image file, Webpack copies it into your
 output directory and returns the final, *public* path to that file.
@@ -60,10 +60,10 @@ To render inside Twig, use the ``asset()`` function:
 .. code-block:: html+twig
 
     {# assets/images/logo.png was copied to public/build/logo.png #}
-    <img src="{{ asset('build/logo.png') }}">
+    <img src="{{ asset('build/logo.png') }}" alt="ACME logo">
 
     {# assets/images/subdir/logo.png was copied to public/build/subdir/logo.png #}
-    <img src="{{ asset('build/subdir/logo.png') }}">
+    <img src="{{ asset('build/subdir/logo.png') }}" alt="ACME logo">
 
 Make sure you've enabled the :ref:`json_manifest_path <load-manifest-files>` option,
 which tells the ``asset()`` function to read the final paths from the ``manifest.json``