updates to complexity pages

[David Meyer <dmm () sprint net>]

        Many people have asked to to update my complexity pages
        with a bit of theoretical background to to support some
        of the material there (in particular, percolation
        theory). So, as promised, I've updated

          http://www.maoz.com/~dmm/complexity_and_the_internet 

        with a little (very little) bit of material on
        percolation theory. 

        Questions and comments on all of this very much welcomed,
        

        Dave