AFAIK, there are no PDF copies of the Drupal documentation that is found on that and the subsequent pages. What makes you think there should be a PDF file there? Have you read or been told something that would lead you to believe that there was one, or were you just making an assumption?
I just feel that it would be convenient to have pdf document. Many tools and website have document in pdf. I feel that there should be a single pdf for all the drupal document.