Add Accessibilty Features section to Select-only combobox example

Author: carmacleod

examples/combobox/combobox-select-only.html

@@ -67,6 +67,20 @@ <h2 id="ex_label">Example</h2>
       <div role="separator" id="ex_end_sep" aria-labelledby="ex_end_sep ex_label" aria-label="End of"></div>
     </section>
 
+    <section>
+      <h2>Accessibility Features</h2>
+      <p>While functionally similar to an HTML select element, there are places where this example diverges from HTML select behavior.</p>
+      <ol>
+        <li>
+          To allow the user to see what is in the listbox, this example opens the listbox when the user types printable characters.
+        </li>
+        <li>
+          To give the user the ability to explore the values with the arrow keys and then cancel and keep the previous value,
+          this example selects on Space, Enter, or loss of focus, and can be cancelled with Escape.
+        </li>
+      </ol>
+    </section>
+
     <section>
       <h2 id="kbd_label">Keyboard Support</h2>
       <p>