Default unsubscribe page and setting default unsubscribe

Default unsubscribe page and setting default unsubscribe. I recorded a video, solved my question, and came up with a new one and a possible UI improvement regarding Brevo Default Unsubscribe Page and how to set the default unsubscribe page.

(Brevo Default Unsubscribe Page)

@Mohit @RDuclos what do you think?