Remove mention of grid and tablist

See w3c/aria#915

Fixes #1156.

Author: zcorpan

aria-practices.html

@@ -3742,7 +3742,7 @@ <h3>What ARE Accessible Names and Descriptions?</h3>
          For example, a switch button named <q>Mute Conversation</q> in the <q>off</q> state could be announced as <q>Mute Conversation switch button off</q>.
         Because descriptions are optional strings that are usually significantly longer than names, they are presented last, sometimes after a slight delay.
         For example, <q>Mute Conversation Switch button off, Silences alerts and notifications about activity in this conversation.</q>
-        To reduce verbosity, some screen readers do not announce descriptions by default but instead inform users of their presence so that users can press a key that will announce the description. 
+        To reduce verbosity, some screen readers do not announce descriptions by default but instead inform users of their presence so that users can press a key that will announce the description.
       </p>
     </section>
 
@@ -4074,7 +4074,7 @@ <h5>Naming Tables and Figures with Captions</h5>
 &lt;/figure></code></pre>
           <p>
             Like with <code>table</code> elements, if a <code>figure</code> is not named using <code>aria-label</code> or <code>aria-labelledby</code>, the content of the <code>figcaption</code> element will be used as the accessible name.
-            However unlike <code>table</code> elements, if the <code>figcaption</code> element is not used for the name, it does not become an accessible description unless it is referenced by <code>aria-describedby</code>. 
+            However unlike <code>table</code> elements, if the <code>figcaption</code> element is not used for the name, it does not become an accessible description unless it is referenced by <code>aria-describedby</code>.
             Nevertheless, assistive technologies will render the content of a <code>figcaption</code> regardless of whether it is used as a name, description, or neither.
           </p>
           <p>Using the <code>caption</code> element to name a <code>table</code> element, or a <code>figcaption</code> element to name a <code>figure</code> element, satisfies <a href="#naming_rule_visible_text">Rule 2: Prefer Visible Text</a> and <a href="#naming_rule_native_techniques">Rule 3: Prefer Native Techniques</a>.</p>
@@ -6287,9 +6287,8 @@ <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>
@@ -6391,11 +6390,6 @@ <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">