introduction to EARL updated

Hi folks,

I updated my EARL by example thing.
http://www.w3.org/2001/sw/Europe/talks/200311-earl/all.en.htm

main change is to explain in detail how to extend result types (this came up
as an actual query for Hera)

I'll also try to get the talk I gave at OzEWAI (which explains the idea of
EARL while avoiding the code) online.

Cheers

Chaals