title: CORS error with ajax request
body: <p>i'm doing this request in ajax but i still have this following error about CORS:
  XMLHttpRequest cannot load <a href="https://cubber.zendesk.com/api/v2/organizations/37520251/users.json" rel="noreferrer">https://cubber.zendesk.com/api/v2/organizations/37520251/users.json</a>. Request header field Access-Control-Allow-Origin is not allowed by Access-Control-Allow-Headers in preflight response.
  Can you help me pls ( i have seen many topic and i still don't understand why it is not working </p>
  
  <pre><code> function afficheorga(a){
        $.ajax({
            url: "https://cubber.zendesk.com/api/v2/users/"+a+"/organizations.json",
            type: 'GET',
            dataType: 'json',
            cors: true ,
            contentType:'application/json',
            secure: true,
                      headers: {
                          'Access-Control-Allow-Origin': '*',
                      },
            beforeSend: function (xhr) {
                xhr.setRequestHeader ("Authorization", "Basic " + btoa(""));
            },
            success: function (data){
              console.log(data.organizations[0].name);
              var organisation = data.organizations[0].name;
              $("#company").text(organisation);
            }
          })
      }
  </code></pre>