Remove mention of grid and tablist

See w3c/aria#915

Fixes #1156.

aria-practices.html

@@ -6419,9 +6419,8 @@ <h2>Describing Hierarchical Structure with <code>aria-level</code></h2>
     <ul>
       <li><code>heading</code></li>
       <li><code>listitem</code></li>
+      <li><code>treeitem</code></li>
       <li><code>row</code></li>
-      <li><code>tablist</code> (not recommended)</li>
-      <li><code>grid</code> (not recommended)</li>
     </ul>
     <section id="aria-level_heading_role">
       <h3><code>heading</code> Role</h3>
@@ -6523,11 +6522,6 @@ <h3><code>row</code> Role</h3>
       <p>Do not use <code>aria-level</code> on rows that are in a <code>grid</code> or a <code>table</code> because only rows in a <code>treegrid</code> table are expected to have a hierarchical relationship.</p>
     </section>
 
-    <section id="aria-level_grid_role">
-      <h3><code>grid</code> Role</h3>
-      <p>The attribute <code>aria-level</code> can be used on elements with role <code>grid</code> to represent nested grids but it is not recommended.</p>
-    </section>
-
   </section>
 
   <section id="presentation_role">