Add German translations (#303)

Author: took

config/web/params.php

@@ -16,7 +16,7 @@
     ],
 
     'locale' => [
-        'locales' => ['en' => 'en-US', 'ru' => 'ru-RU'],
+        'locales' => ['en' => 'en-US', 'ru' => 'ru-RU', 'de' => 'de-DE'],
         'ignoredRequests' => [
             '/debug**',
         ],

resources/messages/de/app.php

@@ -0,0 +1,9 @@
+<?php
+
+declare(strict_types=1);
+
+return [
+    'site.hello' => 'Hallo',
+    'site.start_with' => 'Lass uns etwas Großartiges mit <strong>Yii3</strong> starten!',
+    'site.guide_remind' => 'Vergiss nicht, die Anleitung zu lesen',
+];