bug #4120 Fix use mistakes (mbutkereit)

This PR was submitted for the master branch but it was merged into the 2.3 branch instead (closes #4120).

Discussion
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Fix use mistakes

| Q             | A
| ------------- | ---
| Doc fix?      | yes
| New docs?     |  no
| Applies to    | all

On http://symfony.com/doc/current/components/config/resources.html at "new YamlUserLoader", we have also a missing "use" statement. But i'm not sure if we need there one.

Commits
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7016c82 Fixing a mistake
4353d1f Fix use mistakes.

Author: weaverryan

components/console/introduction.rst

@@ -140,6 +140,9 @@ output. For example::
 It is possible to define your own styles using the class
 :class:`Symfony\\Component\\Console\\Formatter\\OutputFormatterStyle`::
 
+    use Symfony\Component\Console\Formatter\OutputFormatterStyle;
+
+    // ...
     $style = new OutputFormatterStyle('red', 'yellow', array('bold', 'blink'));
     $output->getFormatter()->setStyle('fire', $style);
     $output->writeln('<fire>foo</fire>');

components/templating/helpers/assetshelper.rst

@@ -74,6 +74,8 @@ Asset path generation is handled internally by packages. The component provides
 
 You can also use multiple packages::
 
+    use Symfony\Component\Templating\Asset\PathPackage;
+    
     // ...
     $templateEngine->set(new AssetsHelper());