Fix grammatically incorrect sentence (copy-paste oversight?)

Author: leocassarani

docs/index.html

@@ -1237,7 +1237,7 @@ <h2>Default styles</h2>
                 <li>
                   <label>
                     <input type="radio" name="optionsRadios" value="option2" />
-                    <span>Option two can is something else and selecting it will deselect options 1</span>
+                    <span>Option two is something else and selecting it will deselect option 1</span>
                   </label>
                 </li>
               </ul>