title: How to create collection in Cloud Firestore from Javascript?
body: <p>When user creates account in my angular app, my app creates user account (using Firebase API) with email and password. But also I want to create new collection to hold more data like name, surname...</p>
  
  <p>Each collection's name will have uid.
  But I don't know how to force it? 
  <code>db.createCollection('abcXdefX')</code> doesn't exist. 
  I've no idea what to do. Please, help.</p>