Linkbrowser wizard popup has no rel attribute field for link
The CKEDITOR extensions supports the link relationship attribute, but the "LinkBrowser (ext:recordlist)" for pages/files/external_links does not have any option for that. Used in the header link and typolinks outside the rte_ckeditor extension.
Just had a look into the "AbstractLinkBrowserController" and could not find any possibility to add the rel part to the link browser pop up with usage of hooks or TCA config.
We should have the same behaviour in the recordlist as the rte_ckeditor link browser.