Small Update to SW123

Small update on my Semantic Web 1-2-3 document:

2002-09-09: Added note about origins of the term "Semantic Web", added Making a Semantic Web, and A Rough Guide to N3, and clarified the reasonings why I didn't like RDF/XML in the first place (in an attempt to meet new readers on level ground, as well as to stress I no longer feel that way), and now correctly validates under XHTML/CSS.