docs(Button): add rounded section with ui prop

docs/content/2.elements/3.button.md

@@ -112,6 +112,26 @@ props:
 Button
 ::
 
+### Rounded
+
+To customize the border radius of the Button, you can use the `ui` prop.
+
+::component-card
+---
+props:
+  ui:
+    rounded: 'rounded-full'
+excludedProps:
+  - ui
+---
+
+Button
+::
+
+::callout{icon="i-heroicons-light-bulb"}
+You can customize the whole [preset](#preset) by using the `ui` prop.
+::
+
 ### Icon
 
 Use any icon from [Iconify](https://icones.js.org) by setting the `icon` prop by using this pattern: `i-{collection_name}-{icon_name}`.