Custom domain for article preview

###What’s new? In the Purple Hub, you now have the option to customise the URL for the preview of your content post. This gives you control over how preview URLs are generated, for example for your news articles. ###Your benefit Currently, the Purple Hub generates preview URLs using a default format, which may not match your requirements. By adding the ability for users to configure preview URLs, you can ensure that the preview URLs matches your website structure and specific needs. ###Key facts * A new option to determine the URL under which the preview of a post is displayed in the Purple Hub * Configurable by admins * Condition is the usage of the new background publishing.