This modification adds the option to send registration notifications to members regardless of their permissions, specified in the Registration Settings area.
To navigate there: Admin -> Registration -> Settings.
In the Registration Settings area you will see a new option, "Notify additional members when a new member joins". This is where you specify which members to send notifications to. It takes advantage of SMF 2.0's auto complete feature so you can easily find the members you want and have them listed nicely.