If everything is mentioned on the first page, why, exactly, are there other pages? Documents like this are written by committee and go through many drafts. The summary page isn't necessarily comprehensive. VGleaks has been releasing Durango information in drips and drops to maximize page views for months now. It is reasonable that they are holding things back, presumably their last dump will be right before the first Microsoft Xbox event.
Also we should both recognize the fact that there are people in this thread calling into question the validity of these documents. They do seem a little suspicious. The tone is oddly marketingish and they only mention things that are already rumored.