Update index.html

modify heading mapping to reflect implementations
fixes #116

index.html

@@ -1334,7 +1334,7 @@ <h3>HTML Element Role Mappings</h3>
             </tr>
             <tr tabindex="-1" id="el-h1-h6">
                 <th><a href="https://www.w3.org/TR/html/sections.html#the-h1-h2-h3-h4-h5-and-h6-elements"><code>h1</code></a>, <a href="https://www.w3.org/TR/html/sections.html#the-h1-h2-h3-h4-h5-and-h6-elements"><code>h2</code></a>, <a href="https://www.w3.org/TR/html/sections.html#the-h1-h2-h3-h4-h5-and-h6-elements"><code>h3</code></a>, <a href="https://www.w3.org/TR/html/sections.html#the-h1-h2-h3-h4-h5-and-h6-elements"><code>h4</code></a>, <a href="https://www.w3.org/TR/html/sections.html#the-h1-h2-h3-h4-h5-and-h6-elements"><code>h5</code></a>, <a href="https://www.w3.org/TR/html/sections.html#the-h1-h2-h3-h4-h5-and-h6-elements"><code>h6</code></a></th>
-                <td class="aria"><a class="core-mapping" href="#role-map-heading"><code>heading</code></a> role, with the <a class="core-mapping" href="#ariaLevel"><code>aria-level</code></a> property set to the element's <a href="https://www.w3.org/TR/html/sections.html#outline-depth">outline depth</a></td>
+                <td class="aria"><a class="core-mapping" href="#role-map-heading"><code>heading</code></a> role, with the <a class="core-mapping" href="#ariaLevel"><code>aria-level</code></a> property set to the number in the element's tag name.</td>
                 <td class="ia2"><div class="general">Use WAI-ARIA mapping</div></td>
                 <td class="uia"><div class="general">Use WAI-ARIA mapping</div></td>
                 <td class="atk"><div class="general">Use WAI-ARIA mapping</div></td>