docs: update BACKERS

***NO_CI***

README.md

@@ -179,6 +179,20 @@ Support this project by becoming a sponsor. Your logo will show up in the Contri
         <a href="https://opencollective.com/wikijs/sponsor/15/website" target="_blank"><img src="https://opencollective.com/wikijs/sponsor/15/avatar.svg"></a>
       </td>
     </tr>
+    <tr>
+      <td align="center" valign="middle" width="192">
+        <a href="https://opencollective.com/wikijs/sponsor/16/website" target="_blank"><img src="https://opencollective.com/wikijs/sponsor/16/avatar.svg"></a>
+      </td>
+      <td align="center" valign="middle" width="192">
+        <a href="https://opencollective.com/wikijs/sponsor/17/website" target="_blank"><img src="https://opencollective.com/wikijs/sponsor/17/avatar.svg"></a>
+      </td>
+      <td align="center" valign="middle" width="192">
+        <a href="https://opencollective.com/wikijs/sponsor/18/website" target="_blank"><img src="https://opencollective.com/wikijs/sponsor/18/avatar.svg"></a>
+      </td>
+      <td align="center" valign="middle" width="192">
+        <a href="https://opencollective.com/wikijs/sponsor/19/website" target="_blank"><img src="https://opencollective.com/wikijs/sponsor/19/avatar.svg"></a>
+      </td>
+    </tr>
   </tbody>
 </table>
 </div>