design: test-email - the help menu leads to the Test message topic

The topic was added to the Overview group without its entry in the help's
side menu, which lists every topic of the group in order. check.py: 0
violations.

Co-Authored-By: Claude Opus 5.5 <noreply@anthropic.com>

docs/assets/panel-redesign/panel/help.html

@@ -80,6 +80,7 @@
           <ul class="menu-list">
             <li><a class="is-active" href="#checks"><i class="ti ti-activity-heartbeat"></i>Health checks</a></li>
             <li><a href="#certificate"><i class="ti ti-certificate"></i>TLS certificate</a></li>
+            <li><a href="#test-message"><i class="ti ti-send"></i>Test message</a></li>
             <li><a href="#rdns"><i class="ti ti-arrows-exchange"></i>Reverse DNS</a></li>
           </ul>
           <p class="menu-label">Outbound</p>

docs/assets/panel-redesign/panel/src/help.html

@@ -14,6 +14,7 @@
           <ul class="menu-list">
             <li><a class="is-active" href="#checks"><i class="ti ti-activity-heartbeat"></i>Health checks</a></li>
             <li><a href="#certificate"><i class="ti ti-certificate"></i>TLS certificate</a></li>
+            <li><a href="#test-message"><i class="ti ti-send"></i>Test message</a></li>
             <li><a href="#rdns"><i class="ti ti-arrows-exchange"></i>Reverse DNS</a></li>
           </ul>
           <p class="menu-label">Outbound</p>