nginx: Listen for ACME challenges on port 80 too.

This should make Certbot renewals more reliable.

Signed-off-by: Anders Kaseorg <anders@zulipchat.com>

puppet/zulip/templates/nginx/zulip-enterprise.template.erb

@@ -3,7 +3,12 @@
 server {
     listen 80;
     listen [::]:80;
-    return 301 https://$host$request_uri;
+
+    location / {
+        return 301 https://$host$request_uri;
+    }
+
+    include /etc/nginx/zulip-include/certbot;
 }
 <% end -%>