Editorial: add some <hr>s sectioning off dialog content attributes

Part of whatwg#10963.

source

@@ -61753,6 +61753,8 @@ interface <dfn interface>HTMLDialogElement</dfn> : <span>HTMLElement</span> {
 &lt;/dialog></code></pre>
   </div>
 
+  <hr>
+
   <p>The <dfn element-attr for="dialog"><code data-x="attr-dialog-open">open</code></dfn> attribute
   is a <span>boolean attribute</span>. When specified, it indicates that the <code>dialog</code>
   element is active and that the user can interact with it.</p>
@@ -61825,6 +61827,7 @@ interface <dfn interface>HTMLDialogElement</dfn> : <span>HTMLElement</span> {
   <p>The <code data-x="attr-tabindex">tabindex</code> attribute must not be specified on
   <code>dialog</code> elements.</p>
 
+  <hr>
 
   <dl class="domintro">
    <dt><code data-x=""><var>dialog</var>.<span subdfn data-x="dom-dialog-show">show</span>()</code></dt>
@@ -61873,7 +61876,6 @@ interface <dfn interface>HTMLDialogElement</dfn> : <span>HTMLElement</span> {
    </dd>
   </dl>
 
-
   <div w-nodev>
 
   <p>To <dfn>queue a dialog toggle event task</dfn> given a <code>dialog</code> element