Inserts a new note for a given user. The current time is automatically prepended to the note, so you don't need to add that yourself.
- $user_id (int) - The ID of the user to add a note for.
- $note (string) - The note you wish to add to the user.
rcp_add_member_note( $user_id, __( 'Expiration notice was emailed to the member.', 'rcp' ) );