Review prefix consistency in examples

[rob-metalinkage]

This is the list of prefixes I had to bind to validate the examples...

ex: http://example.org/data/
qudt: http://qudt.org/
qudt-1-1: http://qudt.org/
qunit: http://qudt.org/vocab/unit/
rdfs: http://www.w3.org/2000/01/rdf-schema#
xsd: http://www.w3.org/2001/XMLSchema#
sh: http://www.w3.org/ns/shacl#
owl: http://www.w3.org/2002/07/owl#
sosa: http://www.w3.org/ns/sosa/
ssn-system: http://www.w3.org/ns/ssn/systems/

many examples have these explicitly, but not all - I think we should be consistent - its not necessary to include any we put in a list of assumed bindings up front.

[dr-shorthair]

Working on it in https://github.com/w3c/sdw-sosa-ssn/tree/update-examples-2

[dr-shorthair]

See #271