additional secure headers

config/environments/production.rb

@@ -100,9 +100,11 @@ Rails.application.configure do
     'X-Content-Type-Options'  => 'nosniff',
     'X-XSS-Protection'        => '1; mode=block',
     'Referrer-Policy'         => 'same-origin',
+    'X-Download-Options'      => 'noopen',
+    'X-Robots-Tag'            => 'none',
+    'X-Permitted-Cross-Domain-Policies' => 'none',
     'Strict-Transport-Security' => 'max-age=63072000; includeSubDomains; preload',
-    'X-Clacks-Overhead' => 'GNU Natalie Nguyen'
-
+    'X-Clacks-Overhead'       => 'GNU Natalie Nguyen'
   }
 
   config.x.otp_secret = ENV.fetch('OTP_SECRET')