docs: fix wording on attachment notifications

refs: BGI-5724

Author: Luke Gilfoyle

_site/apis/attach-a-document/1.0/technical-guide/index.html

@@ -194,10 +194,10 @@ <h3 id="notifications" tabindex="-1" class="govuk-heading-m">Notifications</h3>
 <p class="govuk-body">Once the document attachment process finishes, notifications will be available about the status of the attached document via the <a href="apis/notifications" class="govuk-link">Notifications API</a>. Notifications may include:</p>
 <ul class="govuk-list govuk-list--bullet">
 <li>
-<p class="govuk-body"><code class="app-code app-code--inline">application.document-success</code> - the document has successfully been attached to the application</p>
+<p class="govuk-body"><code class="app-code app-code--inline">application.attachment-success</code> - the document has successfully been attached to the application</p>
 </li>
 <li>
-<p class="govuk-body"><code class="app-code app-code--inline">application.document-failed</code> - the document failed to attach to the application</p>
+<p class="govuk-body"><code class="app-code app-code--inline">application.attachment-failed</code> - the document failed to attach to the application</p>
 </li>
 </ul>
 </section>