public-web-static: prevent staging ht ccchh from search machine indexing

config/hosts/public-web-static/virtualHosts/staging.hackertours.hamburg.ccc.de.nix

@@ -33,6 +33,12 @@ in {
 
       root = "${dataDir}";
 
+      # Disallow *, since this is staging and doesn't need to be in any search
+      # results.
+      locations."/robots.txt" = {
+        return = "200 \"User-agent: *\\nDisallow: *\\n\"";
+      };
+
       extraConfig = ''
         # Make use of the ngx_http_realip_module to set the $remote_addr and
         # $remote_port to the client address and client port, when using proxy