firstboot: Link from next steps page to add apps page

- Instead of the apps page which will be empty on first boot.

Tests:

- On Next Steps page, click on apps link takes users to add apps page and not
apps page.

Signed-off-by: Sunil Mohan Adapa <sunil@medhas.org>
Reviewed-by: James Valleroy <jvalleroy@mailbox.org>

plinth/modules/first_boot/templates/firstboot_complete.html

@@ -78,7 +78,7 @@
     <li>
       {% icon 'th' class='svg-icon app-icon' %}
       <div class="step-text">
-        {% url 'apps' as apps_url %}
+        {% url 'apps-add' as apps_url %}
         {% blocktrans trimmed %}
           Put {{ box_name }} to use by installing
           <a href="{{ apps_url }}" target="_blank">apps</a>.