title: createdAt missing in dynamodb item entry
body: <p>I have a <code>dynamodb</code> table that I declared using <code>dynamoose</code> as below:</p>
  <pre><code>const schema = new dynamoose.Schema({
      &quot;email&quot;: String,
      &quot;name&quot;: String,
      &quot;vehicleMotor&quot;: {
          &quot;type&quot;: Number,
          &quot;default&quot;: 0
      },
      &quot;vehicleMotorId&quot;: String,
      &quot;vehicleMotorImage1File&quot;: String,
      &quot;vehicleMotorImage2File&quot;: String,
  }, {
      &quot;saveUnknown&quot;: true,
      &quot;timestamps&quot;: true
  });
  </code></pre>
  <p>From my understanding, when I have <code>&quot;timestamps&quot;: true</code> declared, it should have <strong>both</strong> <code>createdAt</code> and  <code>updatedAt</code> field.</p>
  <p>So when I run my code that looks like this</p>
  <pre><code>if (new){
      const newSeller = new Seller({
          &quot;email&quot;: email,
          &quot;name&quot;: name
      })
      var saveResult = await newSeller.save();
  }else{
      var updateResult = await Seller.update( { &quot;email&quot;: email, sellerType: 1 }, {
          &quot;name&quot;: name
      })
  }
  </code></pre>
  <p>and when I checked the inserted/updated data inside Amazon DynamoDB Management Console, there's no <code>createdAt</code>, only <code>updatedAt</code>. By right I should also have <code>createdAt</code> too right? If not, how to make sure <code>createdAt</code> will always be there?</p>