title: CDK RDS public accessible database
body: <p>I want to create a database with cdk that is publicly accessible (dev db). I know how to do it through the Web UI. I need to set the Public accessibility to true and allow my IP as Inbound on the Security Group.</p>
  
  <pre><code>
          const vpc = new ec2.Vpc(this, 'Vpc')
  
          const postgres = new rds.DatabaseInstance(this, 'Postgres', {
              engine: rds.DatabaseInstanceEngine.POSTGRES,
              instanceClass: ec2.InstanceType.of(ec2.InstanceClass.BURSTABLE2, ec2.InstanceSize.MICRO),
              masterUsername: 'postgres',
              vpc,
          })
  </code></pre>
  
  <p>this is my current status, it works fine, but no public access</p>