visibility: hidden !important (#1289)

* visibility: hidden !important

* CHANGELOG.md

* docs

* docs fix

docs/documentation/modifiers/helpers.html

@@ -37,7 +37,7 @@ doc-subtab: helpers
           <td>Removes any <strong>padding</strong></td>
         </tr>
         <tr>
-          <th rowspan="5">Other</th>
+          <th rowspan="6">Other</th>
           <td><code>is-overlay</code></td>
           <td>Completely covers the first positioned parent</td>
         </tr>
@@ -56,6 +56,10 @@ doc-subtab: helpers
           <td><code>is-unselectable</code></td>
           <td>Prevents the text from being <strong>selectable</strong></td>
         </tr>
+        <tr>
+          <td><code>is-invisible</code></td>
+          <td>Adds visibility <strong>hidden</strong></td>
+        </tr>
       </tbody>
     </table>
   </div>