Add xlink namespace to URL validation error type XML

Author: leonardolara

reference/uri/uri.whatwg.urlvalidationerrortype.xml

@@ -1,5 +1,5 @@
 <?xml version="1.0" encoding="utf-8"?><!-- EN-Revision: 66d06b9c7c95ead73080ea7f0ac25dd11a052f71 Maintainer: lacatoire Status: ready -->
-<reference xml:id="enum.uri-whatwg-urlvalidationerrortype" role="enum" xmlns="http://docbook.org/ns/docbook">
+<reference xml:id="enum.uri-whatwg-urlvalidationerrortype" role="enum" xmlns:xlink="http://www.w3.org/1999/xlink" xmlns="http://docbook.org/ns/docbook">
  <title>A enumeração Uri\WhatWg\UrlValidationErrorType</title>
  <titleabbrev>Uri\WhatWg\UrlValidationErrorType</titleabbrev>