Translate frontend/src/i18n/en.json in ar

99% of minimum 50% translated source file: 'frontend/src/i18n/en.json'
on 'ar'.

Sync of partially translated files: 
untranslated content is included with an empty translation 
or source language content depending on file format

frontend/src/i18n/ar.json

@@ -24,6 +24,7 @@
     "ok": "موافق",
     "permalink": "الحصول على رابط دائم",
     "previous": "السابق",
+    "preview": "Preview",
     "publish": "نشر",
     "rename": "إعادة تسمية",
     "replace": "استبدال",