title: Basic jq usage. How to get nested value
body: <p>This must be incredibly simple but the man page makes no sense to me.
  <code>curl example.com/json</code> gives me</p>
  
  <pre><code>{
   "stats": {
    "storage_server.disk_total": XXXXXXXXXX
   },
   "counters": {}
  }
  </code></pre>
  
  <p>and I want to extract the value <code>XXXXXXXXXX</code> of the disk_total. What is the syntax to do this?</p>