add vault and mongo db with postgres in comments

vault/src/app.ts

@@ -0,0 +1,16 @@
+import express from 'express'
+import { buildClient } from './db'
+
+const app = express()
+
+const dbClient = buildClient('db', 'rushvault', 'rushvault', 'rushvault')
+
+app.get('/api/person', async (req, res) => {
+  res.status(200).send('potato!')
+})
+
+app.listen(8080, async () => {
+  console.log('starting on 8080')
+  dbClient.connect()
+  console.log(await dbClient.query('SELECT NOW()'))
+})