Add content headers to config (#3731)

* add content header

* add content header

* fix format

* fix format

docker/production/nginx.prod.conf

@@ -46,6 +46,9 @@ server {
 
         # Media files require user authentication
         auth_request /auth;
+
+        # Content header to force download
+        add_header Content-disposition "attachment";
     }
 
     # Use the 'user' API endpoint for auth