Add section to set Apache Server file permissions for WordPress

Check the article [WordPress File Permissions: Complete Beginner’s Guide](https://www.malcare.com/blog/wordpress-file-permissions/) on [malcare's security blog](https://www.malcare.com/blog/) and the [WordPress support](https://wordpress.org/support/) article [Hardening WordPress](https://wordpress.org/support/article/hardening-wordpress/).