docs: add note for clarification (#9)

docs/index.md

@@ -7,7 +7,9 @@ position: 1
 
 # Preview
 
-The following example previews Kendo UI components for Angular styled with the Material theme.
+The following example previews Kendo UI components which are styled with the Material theme.
+
+> The Material theme is under active development and is not supported by the whole suite. All components which are available for styling with the Material theme are included in the preview.
 
 {% theme_preview theme:material %}
 <script async src="{% asset_path theme-preview.js %}"></script>