title: Add a unique ID to a button in Wordpress
body: <p>I have a Wordpress one-pager (salient theme using visual composer) with four buttons.</p>
  
  <p>Every one is linked to the same contact form, which is correct.</p>
  
  <p>Now I want to add a specific ID to each button in order to track which one is most effective in Google Analytics.</p>
  
  <p>I track my other events using Google Tag Manager.</p>