title: how to add script in <head> section of prestashop
body: <p>how to add following code</p>
  
  <pre><code>&lt;script src="https://clientcdn.pushchant.com/core/rp.js"&gt;&lt;/script&gt;  &lt;script&gt;
      _pe.subscribe();
  &lt;/script&gt;
  </code></pre>
  
  <p>in head section of prestashop 1.7</p>
  
  <p>And also tell me how to add service-worker.js in root directory of prestashop.</p>
  
  <p>or</p>
  
  <p>can be add service-worker.js other than root directory</p>