Add several paragraphs and examples to Overview section.

[bobdc]

Note that some of the original Overview content has been commented out as opposed to removed. See the comment I added to it.

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[pfps]

The lead example needs to be changed. Dates are not part of the core of RDF. Even if they were, dates in date-aware systems are not strings. An example that uses only the notions are are required to be supported in RDF is needed.

[pfps]

RDF does not allow subjects or objects of triples to be triples. RDF reification is something different - instances of rdf:Statement have an intended meaning that is some sort of description of an RDF triple. The distinction is subtle but profound and if this document is going to make any claim about RDF reification it needs to a completely correct claim.

[pchampin]

@pfps the running example in the RDF 1.1 Primer uses dates.

An example that uses only the notions are are required to be supported in RDF is needed

Furthermore, the example does not rely on any special understanding or recognizing of the date datatype. It is just a literal; How is it not supported in RDF?

[pfps]

The example uses dates, as far as I can tell. These are not necessarily supported in RDF and could be considered to be just like "2004-04-03"^^ex:junk in some RDF systems. Either that or the date in the example is just a string, which is worse.
So either use something that is just a string or avoid literals.

[pchampin]

This was discussed during today's call: https://w3c.github.io/rdf-star/Minutes/2020-12-18.html#item03

[pchampin]

As discussed in today's call: it would be better if the example didn't involve the xsd:date, which could give the wrong impression that all RDF* implementations need to recognize that datatype.

[pchampin]

Thanks @bobdc , good to go :)

[bobdc]

Thank you!

[hartig]

Thanks @bobdc for your efforts!

[bobdc]

I just noticed that we never updated the "After declaring a prefix URI" paragraph to reference the the new familyName and jobTitle triples. Should I fix that in a separate pull request or can someone add that in another update?