Voice and tone: Link directly to discussion

Updates the GitHub discussion link to go directly to the relevant discussion.

apps/docs/src/common/pages/content-style-guide/voice-and-tone.tsx

@@ -53,7 +53,7 @@ const Page: FC<PageProps> = ({ location }) => (
       </ul>
 
       <h2>Help improve this guidance</h2>
-      <p>To contribute, join the <A href="https://github.com/UKHomeOffice/design-system/discussions/">GitHub discussion</A>.</p>
+      <p>To contribute, join the <A href="https://github.com/UKHomeOffice/design-system/discussions/600">GitHub discussion</A>.</p>
     </div>
   </div>
 );