title: Create a GitHub webhook for when a pull request is accepted & merged to master
body: <p>I have a webhook that currently fires on <code>push</code> to any branch. This triggers the webhook far too frequently. Ideally, the webhook would only fire when a pull request is <strong>merged</strong> into <code>master</code>. I don't see that as an option, though:</p>
  
  <p><img src="https://i.stack.imgur.com/AIlXE.png" alt="enter image description here"></p>
  
  <p>Is there a way to get additional webhook options or to customize the webhook somehow?</p>