Fix fourth-wall URL.
Fix fourth-wall URL.

The fourth-wall URL requires a trailing '/'.  Without this, the page
returns a 404 (note that http://alphagov.github.io/fourth-wall/?foo=bar
works, whereas http://alphagov.github.io/fourth-wall?foo=bar 404s).

I suspect that github pages may have changed this behaviour recently. If
you use the URL without the trailing / with no query params, it gets
redirected, but not when query params are included.

alphagov/multicloud-deploy,alphagov/multicloud-deploy,alphagov/multicloud-deploy