Add headingoffset/headingreset to attribute index

Author: keithamus

source

@@ -153029,6 +153029,17 @@ interface <dfn interface>External</dfn> {
           <code data-x="attr-tdth-headers">th</code>
      <td> The header cells for this cell
      <td> <span>Unordered set of unique space-separated tokens</span> consisting of IDs*
+    <tr>
+     <th> <code data-x="">headingoffset</code>
+     <td> <span data-x="attr-headingoffset">HTML elements</span>
+     <td> Offset a heading level of child headers by the given amount
+     <td> <span>Valid non-negative integer</span> between 0 and 8
+    <tr>
+     <th> <code data-x="">headingreset</code>
+     <td> <span data-x="attr-headingreset">HTML elements</span>
+     <td> Prevent a heading offset computation from traversing beyond the element with this
+           attribute.
+     <td> <span>Boolean attribute</span>
     <tr>
      <th> <code data-x="">height</code>
      <td> <code data-x="attr-canvas-height">canvas</code>;