title: JavaScript: how to use Braintree paymentMethod nonce bu
body: <p>I am using Braintree v3 for a client implementation. I am using the dropin UI. 
  I am trying to create a new vaulted card. I have an api from the backend team I’m working with to update payment method. It takes a user token in the Header and if successful, the response is a payment method nonce. </p>
  
  <p>I’m just not sure what to do with this paymentMethod nonce or where to actually call the api. </p>