www: remove proprietary dbtree.js script from r96013

This minified source code and artwork is copied from a commercial product and
carries no license information:

  dbtree.js (7 kb), 25.03.2014 14:51:32
  Purchase and download DBTree now for only $29.75 $9.75

It was used by a small TOC which looks fine now as a plain unordered list.