update scripts to match tutorial

[Tutorial](https://blog.apollographql.com/deploy-a-fullstack-apollo-app-with-netlify-45a7dfd51b0b) states these scripts are in the `package.json` but they're not.

Author: gezquinndesign

package.json

@@ -10,6 +10,7 @@
   },
   "scripts": {
     "start": "react-scripts start",
+    "start:lambda": "netlify-lambda serve src/lambda",
     "build": "run-p build:**",
     "build:app": "react-scripts build",
     "build:lambda": "netlify-lambda build src/lambda",