Using completionData cache headers.

Author: isoos

app/lib/frontend/handlers/misc.dart

@@ -40,7 +40,10 @@ Future<shelf.Response> wellKnownSecurityTxtHandler(
       'Policy: https://pub.dev/security\n'
       'Preferred-Languages: en\n'
       'Expires: ${expiresDate}T00:00:00z\n';
-  return shelf.Response.ok(content);
+  return shelf.Response.ok(
+    content,
+    headers: CacheControl.completionData.headers, // 8 hours public cache
+  );
 }
 
 /// Handles requests for /help