Right now, this message says:
List of usernames that are blacklisted from triggering most Echo notifications (edits to your user talk page will still trigger notifications)
It should be more obvious how the Mute feature will work.
Section title: Muted users
Description: Do not display notifications from these users. ([[mw:Help:Notifications#mute|learn more]])
For non-JS, suggestion text: One username per line