title: React-native : Dynamically update header title in stack navigator
body: <p>I have made a custom component for header title(stack navigator)which shows user name along with some image.
  On this page I have to edit the username and on success <strong>Update it in header as well</strong></p>
  
  <p>So my question is <strong>How to change/update title dynamically?</strong></p>