Add gtag code

Author: emeraldjava

gatsby-config.js

@@ -81,6 +81,7 @@ module.exports = {
       options: {
         // You can add multiple tracking ids and a pageview event will be fired for all of them.
         trackingIds: [
+          "330707515",
           "UA-156016480-1" // Google Analytics / GA
         ],
         // This object gets passed directly to the gtag config command