In Citation Resource https://jira.hl7.org/browse/FHIR-33421 we discovered that we were not actually describing types of URLs but rather classifiers of the result obtained at the URLs.  So we removed the webLocation.type element and added a webLocation.classifier element with 0..* CodeableConcept with Extensible binding to ArticleUrlClassifier value set http://build.fhir.org/valueset-artifact-url-classifier.html.