upd gradients

Author: olton

examples/gradients.html

@@ -24,6 +24,9 @@
     <div class="app-bar-item-static no-hover">
         <div class="text-leader">Gradients</div>
     </div>
+    <div class="ml-auto mr-auto">
+        To use gradient you must add classes `gradient` and `gradient-{theme}` to the element: class="gradient gradient-green"
+    </div>
     <div class="app-bar-item-static no-hover ml-auto">
         <input type="checkbox" data-role="theme-switcher"/>
     </div>