change node environment code example

Example 1: set node process production

{
  ...
  "scripts": {
    "start": "NODE_ENV=production node ./app"
  }
  ...
}

Example 2: node how to set environment variable

// get an environment variableexport const token = process.env['API_TOKEN'];// set an environment variable at runtimeprocess.env['RANDOM_ID'] = Math.random();