Normative statement in Security Considerations

[csarven]

Similar issue to issue #181

The Security Considerations section is labeled as non-normative, but it includes content that uses normative terms, such as "SHOULD".

Applications rendering strings retrieved from untrusted RDF documents, or using unescaped characters, SHOULD use warnings and other appropriate means to limit the possibility that malignant strings might be used to mislead the reader.

RDF uses IRIs as term identifiers. Applications interpreting data expressed in RDF SHOULD address the security issues of Internationalized Resource Identifiers (IRIs) [RFC3987] Section 8, as well as Uniform Resource Identifier (URI): Generic Syntax [RFC3986] Section 7.

It'd be preferable to use another term instead of "SHOULD". See also #182