Fix #372

docs/documentation/elements/progress.html

@@ -53,6 +53,14 @@ meta:
 
 {% include elements/anchor.html name="Indeterminate" %}
 
+{% include elements/new-tag.html version="0.7.3" %}
+
+<div class="content">
+  <p>
+    If you don't set the HTML <code>value</code> attribute, you can display an <strong>indeterminate</strong> progress bar. It's used to show that some progress is going on, but the actual duration is not yet determined.
+  </p>
+</div>
+
 {% include elements/snippet.html content=progress_indeterminate %}
 
 {% include elements/variables.html type='element' %}