Add join page with embedded HubSpot form

We need to add a page so people can sign up for the alliance. This page should be under the participation page (/join would work) but does not need to be in the menu.

Here is the embed code:

<script charset="utf-8" type="text/javascript" src="//js.hsforms.net/forms/embed/v2.js"></script>
<script>
  hbspt.forms.create({
    region: "na1",
    portalId: "5413615",
    formId: "0dc47650-e69e-4c28-b730-2f3c57feb3ff"
  });
</script>

CC @aminrasti @fdesbiens