Editorial: "signalling" -> "signaling"

We try to use en-US over en-GB for this spec.

Author: anssiko

index.bs

@@ -3172,7 +3172,7 @@ console.log('Output value: ' + result.outputs.output);
         <td>{{Uint8Array}}
 </table>
 
-<p class="note">{{Float16Array}} is at <a href="https://tc39.es/process-document/">ECMA Stage 3</a> signalling its design is finished. Implementers wanting to enable this type ahead native implementations can emulate the type by passing raw bits via {{Uint16Array}}. <a href="https://github.com/webmachinelearning/webnn/issues/373">[Issue webnn#373]</a></p>
+<p class="note">{{Float16Array}} is at <a href="https://tc39.es/process-document/">ECMA Stage 3</a> signaling its design is finished. Implementers wanting to enable this type ahead native implementations can emulate the type by passing raw bits via {{Uint16Array}}. <a href="https://github.com/webmachinelearning/webnn/issues/373">[Issue webnn#373]</a></p>
 
 <h2 id="acknowledgements">Acknowledgements</h2>