title: Google Cloud Deployment Manager: add instances to instance group via yaml configuration
body: <p>I'm trying to create an unmanaged instanceGroup with several VM's in it via Deployment Manager Configuration (YAML file).</p>
  
  <p>I can easily find docs about <a href="https://cloud.google.com/compute/docs/reference/latest/instanceGroups/addInstances" rel="nofollow noreferrer">addInstances</a> via Google API, but couldn't find docs about how to do this in a YAML file:</p>
  
  <p><a href="https://cloud.google.com/compute/docs/reference/beta/instances" rel="nofollow noreferrer">instances</a></p>
  
  <p><a href="https://cloud.google.com/compute/docs/reference/beta/instanceGroups" rel="nofollow noreferrer">instanceGroups</a></p>
  
  <p>What properties should be included in instances/instanceGroup resource to make it work?</p>