"Relative IRIs" section in the Turtle document

Hi,

following today's discussion about normative/informative sections and the
role of section "3.1.2 Relative IRIs", my suggestion would be

* replace the content of 3.1.2 with a lighter, informative version
(possibly with a reference to the normative section)
* create a new subsection of Sec6 (possibly between 6.1 and 6.2) describing
normatively how relative IRIs are to be resolved
  (by copying the "hardest" parts of current 3.1.2)

It seems to me that it is consistent with the current structure of the
document (which I like, for the record), while answering the need to
centralize all the normative parts in the same place.

Note also that I could live with sections 2, 3 and 4 grouped under a big
Informative umbrella section, but I'm not sure this is really required.

  pa