title: Pagination in firestore api
body: <p>I am trying to paginate documents with firestore beta. I am following the official <a href="https://cloud.google.com/firestore/docs/reference/rest/v1beta1/projects.databases.documents/list" rel="noreferrer">docs</a></p>
  
  <p>I see there is a pageSize param to say how many documents you want to show, but i dont see any offset option. Does anybody know how can i do a pagination system?</p>
  
  <p>thank you</p>