Add tags

docs/documentation/elements/progress.html

@@ -2,6 +2,11 @@
 layout: documentation
 doc-tab: elements
 doc-subtab: progress
+variables:
+- name: $progress-bar-background-color
+  value: $border
+- name: $progress-value-background-color
+  value: $text
 ---
 
 {% include subnav-elements.html %}
@@ -48,5 +53,7 @@ doc-subtab: progress
 <progress class="progress is-large" value="60" max="100">60%</progress>
 {% endhighlight %}
 
+    {% include variables.html element=true %}
+
   </div>
 </section>