The best way to compare this function is with the favourites in the browser. In addition to the standard links (website, Contao backend, Contao manager, Contao install tool), you can add any other links per installation, e.g. for the hosting control panel and/or webmail.
To do so, open the desired installation in the detail view. Then click on the link icon. A list with the existing links is displayed. To add further links, click on "Manage" and you can now add your links as you wish. The sorting can be changed later and, of course, links can also be deleted again.
You can access the links in the detailed view via the "Link icon" or directly via the context menu.