Arabic Translation

[Developer-Incoming]

Hello and thank you for wanting to contribute to the MagicMirror² project!

Please make sure that you have followed these 4 rules before submitting your Pull Request:

1. Base your pull requests against the develop branch.
2. Include these infos in the description:

• Does the pull request solve a related issue?
• If so, can you reference the issue like this Fixes #<issue_number>?
• What does the pull request accomplish? Use a list if needed.
• If it includes major visual changes please add screenshots.

3. Please run npm run lint:prettier before submitting so that
   style issues are fixed.
4. Don't forget to add an entry about your changes to
   the CHANGELOG.md file.

Note: Sometimes the development moves very fast. It is highly
recommended that you update your branch of develop before creating a
pull request to send us your changes. This makes everyone's lives
easier (including yours) and helps us out on the development team.

Thanks again and have a nice day!

[khassel]

Thanks!

@Developer-Incoming there is a minimal code-style issue, the new ar.json file misses a new line at the end.