add Global Privacy Control metadata

nginx/server.conf

@@ -103,7 +103,7 @@ server {
         gzip_static off;
     }
 
-    location ~ "\.(txt|xml)$" {
+    location ~ "\.(json|txt|xml)$" {
         include /etc/nginx/snippets/security-headers.conf;
         add_header Cache-Control "public, max-age=1800";
     }