Things have changed since 4.5.1. The information in that doc is actually from 4.0 and earlier. That document is in need of some love to get it back up to where we are now and we do have a ticket in for this (UEDOC-1011). It’s backlogged at the moment, but for the most part the guide is still fairly accurate from my quick glance. The surface types that go to the DefaultEngine.ini no longer need to have the tag added or restart the engine to get them to show up though.
This is the basics of what it should say now (I’ve just edited out doc file to easily demonstrate):
I hope this helps.