title: PHPStorm use private key to sign commit
body: <p>How do I sign git commit in PhPStorm?</p>
  
  <p>command-line which works (the option '-S'): </p>
  
  <pre><code>git commit -S -m "My message"
  </code></pre>
  
  <p>But cannot find a way to achieve it using PHPStorm.</p>