After the Code of Conduct (T90908: Goal: Binding code of conduct for all Wikimedia technical spaces with consequences for breaches) is approved, the Etherpad footer should link to it.
There is apparently a plugin for this, ep_footer: https://static.etherpad.org/plugins.html .
It could also go in the default text for new pads (etherpad.wikimedia.org -> New Pad), but users editing an existing pad wouldn't see that, so it's not sufficient.