title: How to change default title of a github pull request
body: <p>I'm wondering if it's possible to change the format of a pull request title to my preference. 
  Currently, when I open a pull request from a forked branch, the pull request sets the name of the branch as default title. </p>
  
  <p>For example, I have a branch called <code>FB-123</code> and when I click on the 'Create pull request' button to open a pull request, the title is already set as 
  <code>Fb-123</code> .</p>
  
  <p>But I would like to set a template to be <code>[Fb-123]</code>. </p>
  
  <p>Is this not a feature supported on github? </p>
  
  <p>Thanks in advance for your help :) </p>