Reach Interoperability Guidelines - URI changes

A fix for the URIs in message:
         http://lists.xml.org/archives/xml-dev/200403/msg00309.html

Sorry for this but the launch gremlins arrived on time and I got some of 
the URIs wrong.

Corrected URIs:
         RIGs 2 (XML) (http://sdec.reach.ie/rigs/rig0002)
         RIG 3 (namespaces) (http://sdec.reach.ie/rigs/rig0003),
         RIG 4 (Schema languages) (http://sdec.reach.ie/rigs/rig0004)
         RIG 5 (Unicode)  (http://sdec.reach.ie/rigs/rig0005)
         RIG 6 (Versioning) (http://sdec.reach.ie/rigs/rig0006)

Sean