[css-values] Update the about: registry url, since the IANA broke it.

Author: tabatkins

css-values/Overview.bs

@@ -1743,7 +1743,7 @@ Registration for the <code>about:invalid</code> URL scheme</h3>
 	in accordance with the registration procedure defined in [[RFC6694]].
 
 
-	The official record of this registration can be found at <a href="http://www.iana.org/assignments/about-URL-tokens/about-URL-tokens.xml">http://www.iana.org/assignments/about-URL-tokens/about-URL-tokens.xml</a>.
+	The official record of this registration can be found at <a href="http://www.iana.org/assignments/about-uri-tokens/about-uri-tokens.xhtml">http://www.iana.org/assignments/about-uri-tokens/about-uri-tokens.xhtml</a>.
 
 	<table class="data define">
 		<tr>

css-values/Overview.html

@@ -92,7 +92,7 @@
    <h1 class="p-name no-ref" id="title">CSS Values and Units Module Level 3</h1>
 
    <h2 class="no-num no-toc no-ref heading settled" id="subtitle"><span class="content">Editor’s Draft,
-    <time class="dt-updated" datetime="2015-06-04">4 June 2015</time></span></h2>
+    <time class="dt-updated" datetime="2015-06-08">8 June 2015</time></span></h2>
 
    <div data-fill-with="spec-metadata">
     <dl>
@@ -3306,7 +3306,7 @@ <h3 class="heading settled" data-level="9.1" id="about-invalid"><span class="sec
 
 
 
-   <p>The official record of this registration can be found at <a href="http://www.iana.org/assignments/about-URL-tokens/about-URL-tokens.xml">http://www.iana.org/assignments/about-URL-tokens/about-URL-tokens.xml</a>.</p>
+   <p>The official record of this registration can be found at <a href="http://www.iana.org/assignments/about-uri-tokens/about-uri-tokens.xhtml">http://www.iana.org/assignments/about-uri-tokens/about-uri-tokens.xhtml</a>.</p>
 
 
    <table class="data define">