gEDA-user: [pcb] "first board" docs

[DJ Delorie]

> Third: 555 SMT blinky.  Same thing, but mostly SMT, with a ground
> plane on the back.  This introduces SMT, vias, and thermals.

I'm thinking of something that uses two chips, like a USB to RS232
converter, so I can put stuff on both sides, force vias, etc.  Too
much?

Also, I got some advice for cross-linking terms in the terminology
section.  It only works for HTML, though, to get around the decoration
that @ref{} adds, and only within that section if you split the HTML
file up.  http://www.delorie.com/pcb/docs/gs/