Minor grammatical corrections to index list

* index.html: Minor grammar changes to feature list

index.html

@@ -22,13 +22,13 @@
   <li><a href="#traits">Traits as mixins</a></li>
  <li>
    <a href="#access-modifiers">
-      Access modifiers (public, protected and private)
+      Access modifiers (public, protected, and private)
     </a>
   </li>
   <li><a href="#abstract">Abstract classes and methods</a></li>
   <li><a href="#interfaces">Interfaces</a></li>
   <li><a href="#static">Static and constant members</a></li>
-  <li><a href="#error">Transparent Error Subtyping</a></li>
+  <li><a href="#error">Transparent error subtyping</a></li>
   <li>Support for ECMAScript 3+</li>
 </ul>
 </div>