message: docs: document lazy mounting of tab panels
diff: @@ -310,6 +310,31 @@ tab by pressing <kbd>Space</kbd> or <kbd>Enter</kbd>.
  </Tabs>
  ```
  +### Lazily mounting tab panels
  +
  +By default, the Tabs component renders all tabs to the DOM If you'd like to only mount the contents of a `TabPanel` to the DOM at once.
  +If you want to defer rendering of content until the tab is activated/clicked/selected, you can use the `isLazy` property.
  +In this way, the tab content will not be mounted to the DOM until it is open.
  +
  +```jsx
  +<Tabs isLazy>
  + <TabList>
  + <Tab>One</Tab>
  + <Tab>Two</Tab>
  + </TabList>
  + <TabPanels>
  + {/* initially mounted */}
  + <TabPanel>
  + <p>one!</p>
  + </TabPanel>
  + {/* initially not mounted */}
  + <TabPanel>
  + <p>two!</p>
  + </TabPanel>
  + </TabPanels>
  +</Tabs>
  +```
  +
  ### Controlled Tabs
  Like form inputs, a tab's state can be controlled. Make sure to include an
  