[gta02-core] Overview collections update

[Werner Almesberger]

I made a few small changes to the overview files that should help
with reviews:

- made a link page:
  http://people.openmoko.org/werner/gta02-core.html

- added the main schematics

- added PDF versions as well

The schematics come pre-shrunk to A4. The link page is static.
The files it links to get updated whenever I notice that
something has changed.

- Werner