metamodel property about link to LegalRuleML

<rdf:Property rdf:about="#hasLegalRuleMLXMLExpression">
    <rdfs:label>has LegalRuleML/XML _expression_</rdfs:label>
    <rdfs:comment>a LegalRulelML XML-based _expression_ of the LegalRuleML document.</rdfs:comment>
    <rdfs:domain rdf:resource="#LegalRuleMLDocument"/>
  </rdf:Property>