installing webpack-encore and yarn in node container

app/config/bundles.php

@@ -9,4 +9,5 @@ return [
     Doctrine\Bundle\DoctrineBundle\DoctrineBundle::class => ['all' => true],
     Doctrine\Bundle\MigrationsBundle\DoctrineMigrationsBundle::class => ['all' => true],
     Symfony\Bundle\MakerBundle\MakerBundle::class => ['dev' => true],
+    Symfony\WebpackEncoreBundle\WebpackEncoreBundle::class => ['all' => true],
 ];