chore(starters): Add empty gatsby-config.js (#13951)

gatsby-config.js

@@ -0,0 +1,9 @@
+/**
+ * Configure your Gatsby site with this file.
+ *
+ * See: https://www.gatsbyjs.org/docs/gatsby-config/
+ */
+
+module.exports = {
+  /* Your site config here */
+}