title: Dynamic Querying in AngularFirestore2 with snapshotChanges()
body: <p>Using the example provided by the AngularFire2 docs I'm able to set a dynamic query that returns an observable of valueChanges().</p>
  
  <p>Example found here:
  <a href="https://github.com/angular/angularfire2/blob/master/docs/firestore/querying-collections.md" rel="nofollow noreferrer">https://github.com/angular/angularfire2/blob/master/docs/firestore/querying-collections.md</a></p>
  
  <p>How does one accomplish the same thing but with snapshotChanges()?</p>
  
  <p>I'm looking to get the document id associated with each document.</p>