Include omitted container example

Author: stevepiercy

docs/install/containers/examples/index.md

@@ -18,6 +18,7 @@ nginx-volto-plone-zeo
 nginx-volto-plone-postgresql
 nginx-plone
 haproxy-plone-zeo
+traefik-volto-plone-varnish
 ```
 
 Examples of projects running Plone using `docker compose`.
@@ -29,3 +30,4 @@ Examples of projects running Plone using `docker compose`.
 | [nginx-volto-plone-postgresql](nginx-volto-plone-postgresql) | Stack with nginx, Frontend, Backend, and PostgreSQL DB |
 | [nginx-plone](nginx-plone) | Stack with nginx and Backend (Plone Classic) |
 | [haproxy-plone-zeo](haproxy-plone-zeo) | Stack with HAProxy, Backend, and ZEO server |
+| [traefik-volto-plone-varnish](traefik-volto-plone-varnish) | Stack with traefik, Frontend, Backend, Varnish |