title: Disable merge button on GitHub till a pull request is approved
body: <p>I want to achieve merge button diable functionality similar to <code>STASH</code> in <code>GitHub</code> where the button is disabled till a pull request is approved. By default, <code>GitHub</code>  pull requests are always able to merge i.e. merge button is enabled, disregard of approval from peers. </p>
  
  <p> Any suggestions how can I achieve this goal ?</p>