docs: more appropriate terminology ("highlight" -> "focus")

docs/_includes/examples/basics.html

@@ -69,13 +69,13 @@ $(".js-example-basic-multiple").select2();
   <div class="s2-example">
     <p>
       <label for="id_label_single">
-        Click this to highlight the single select element
+        Click this to focus the single select element
         <select class="js-example-basic-single js-states form-control" id="id_label_single"></select>
       </label>
     </p>
     <p>
       <label for="id_label_multiple">
-        Click this to highlight the multiple select element
+        Click this to focus the multiple select element
         <select class="js-example-basic-multiple js-states form-control" id="id_label_multiple" multiple="multiple"></select>
       </label>
     </p>