change classname from .btn-dark to .btn-inverse, change use text

docs/base-css.html

@@ -1285,6 +1285,11 @@ For example, <code>section</code> should be wrapped as inline.
         <td><a class="btn btn-danger" href="#">Danger</a></td>
         <td><code>.btn-danger</code></td>
         <td>Indicates a dangerous or potentially negative action</td>
+      </tr>
+  	  <tr>
+        <td><a class="btn btn-inverse" href="#">Inverse</a></td>
+        <td><code>.btn-inverse</code></td>
+        <td>Alternate dark gray button, not tied to a semantic action or use</td>
       </tr>
     </tbody>
   </table>