[Lsb-infrastructure] Snapshot specifications have moved

[Wichmann, Mats D]

To make it a little more clear that the snapshot
specs on the web are just that, the paths have now
changed.

Please update any links you may have to use:

http://www.linux-foundation/org/snapshots/books
http://www.linux-foundation/org/snapshots/booksets

without the snapshots/ part, it won't find them
any longer.  I think ispras were the only
consumers of these links so far, they haven't
been widely publicised.