Document #12476 bug in the wall of bugs

docs/browser-bugs.html

@@ -107,6 +107,12 @@ lead: "A list of the browser bugs that Bootstrap is currently grappling with."
           <td>(No public bug tracker)</td>
           <td><a href="https://github.com/twbs/bootstrap/issues/9774">#9774</a></td>
         </tr>
+        <tr>
+          <td>Internet Explorer 8</td>
+          <td>Buttons in justified button groups have no borders unless each button is wrapped in an extra button group</td>
+          <td>(No public bug tracker)</td>
+          <td><a href="https://github.com/twbs/bootstrap/issues/12476">#12476</a></td>
+        </tr>
       </tbody>
     </table>
   </div>