Add example of PaNET being used

Motivation:

A recent commit (dc00bc2) removed the class `dataset`, the object
property `hasTechnique` and several named individuals (techniques and
datasets) from the PaNET ontology.  These were removed because they were
superfluous and potentially confusing.

Nevertheless, the removed items are potentially useful as an example,
showing how PaNET may be used.

Such examples also play a part in resolving issue #119.

Finally, the example may prove useful as material by which the PaNET
ontology may be validated.

Modification:

Added an example file that recreates the example items that were
removed, albeit uses a concrete IRI for the terms.

Result:

Add the first example of how PaNET may be used.

examples/example-1.ttl

@@ -0,0 +1,75 @@
+@prefix owl: <http://www.w3.org/2002/07/owl#> .
+@prefix rdf: <http://www.w3.org/1999/02/22-rdf-syntax-ns#> .
+@prefix rdfs: <http://www.w3.org/2000/01/rdf-schema#> .
+@prefix PaNET: <http://purl.org/pan-science/PaNET/> .
+@prefix eg: <http://purl.org/pan-science/PaNET/example-1#> .
+@prefix obo: <http://purl.obolibrary.org/obo/> .
+
+#
+#  Items to be identified
+#
+
+eg:dataset a owl:Class;
+    rdfs:label "dataset";
+    obo:IAO_0000115 "A dataset in the domain of neutron, muon and accelerator-based light sources";
+    .
+
+#
+#  Object properties
+#
+
+eg:hasTechnique a owl:ObjectProperty;
+    rdfs:label "hasTechnique";
+    .
+
+#
+#  Specific techniques
+#
+
+eg:myARPEStechnique a owl:NamedIndividual,
+        PaNET:PaNET01089;
+    rdfs:label "myARPEStechnique";
+    .
+
+eg:myHighResNeutronPowderDiffractionTechnique a owl:NamedIndividual,
+        PaNET:PaNET01234;
+    rdfs:label "myHighResNeutronPowderDiffractionTechnique";
+    .
+
+eg:myMicrofocusX-rayAbsorptionSpectroscopyTechnique a owl:NamedIndividual,
+        PaNET:PaNET01322;
+    rdfs:label "myMicrofocusX-rayAbsorptionSpectroscopyTechnique";
+    .
+
+eg:mySingleCrystalDiffractionTechnique a owl:NamedIndividual,
+        PaNET:PaNET01029;
+    rdfs:label "mySingleCrystalDiffractionTechnique";
+    .
+
+#
+#  Specific datasets
+#
+
+eg:my_ARPES_data a owl:NamedIndividual,
+        eg:dataset;
+    eg:hasTechnique eg:myARPEStechnique;
+    rdfs:label "my_ARPES_data";
+    .
+
+eg:my_microfocus_spectrosopy_data a owl:NamedIndividual,
+        eg:dataset;
+    eg:hasTechnique eg:myMicrofocusX-rayAbsorptionSpectroscopyTechnique;
+    rdfs:label "my_microfocus_spectrosopy_data";
+    .
+
+eg:my_neutron_powder_diffraction_diffraction_data_55 a owl:NamedIndividual,
+        eg:dataset;
+    eg:hasTechnique eg:myHighResNeutronPowderDiffractionTechnique;
+    rdfs:label "my_neutron_powder_diffraction_diffraction_data_55";
+    .
+
+eg:my_single_crystal_x-ray_diffraction_data_123 a owl:NamedIndividual,
+        eg:dataset;
+    eg:hasTechnique eg:mySingleCrystalDiffractionTechnique;
+    rdfs:label "my_single_crystal_x-ray_diffraction_data_123";
+    .