[css-writing-modes-3] Update ref from HTML5 to HTML

* Other places in the spec already use the Living Standard as the
  refernce
* /TR/html5/ is a redirect to the Living Standard anyway
* The section numbering between the LS and the TR version is different,
  so the redirect without changing the section number was confusing

Author: frivoal

css-writing-modes-3/Overview.bs

@@ -209,7 +209,7 @@ Inline Direction and Bidirectionality</h2>
     to its corresponding CSS styles.
 
   <p class="note">
-    The HTML specifications ([[HTML401]], section 8.2, and [[HTML5]], section 10.3.5) define
+    The HTML specifications ([[HTML401]], section 8.2, and [[HTML]] [[HTML#bidi-rendering|section 14.3.5]]) define
     bidirectionality behavior for HTML elements.</p>
 
   <p class="advisement">