title: select2 - initselection error
body: <p>I am getting the following error when using select2 plugin on <code>initSelection</code>.</p>
  
  <p><code>Error: Uncaught Error: No select2/compat/initSelection</code> is the error I am getting.</p>
  
  <p>Hope somebody helps me in sorting out the <code>inistselection</code> issue.</p>
  
  <p>JS:</p>
  
  <pre><code>  $(".doctor_id_pat").select2({
      placeholder: "Search Users",
      minimumInputLength: 2,
      ajax: {
          url: "/listallergiesajax",
          dataType: 'json',
          data: function(term) {
              return {
                  q: term
              };
          },
          results: function(data, page) {
              return {
  
                  results: $.map(data, function(item) {
  
                      return {
                          text: item.text,
                          id: item.id
                      }
                  })
  
              };
          },
      },
      initSelection: function(element, callback) {
  
          $.ajax("/listallergiesajax", {
              dataType: "json"
          }).done(function(data) {
  
              callback(data.results[0]);
  
          });
      }
  });
  </code></pre>