Add a copy of the Verifiable Data Structures paper to docs so we can more easily link to it.
Add a copy of the Verifiable Data Structures paper to docs so we can
more easily link to it.

codingllama/trillian,RJPercival/trillian,gdbelvin/trillian,Martin2112/trillian,gtank/trillian,Martin2112/trillian,RJPercival/trillian,AlCutter/trillian,codingllama/trillian,gdbelvin/trillian,daviddrysdale/trillian,google/trillian,AlCutter/trillian,daviddrysdale/trillian,Martin2112/trillian,google/trillian,daviddrysdale/trillian,gdbelvin/trillian,gtank/trillian