Fix misleading docs

docs/src/pages/configurations/add-custom-body/index.md

@@ -8,7 +8,7 @@ Sometimes, you may need to add different tags to the HTML body. This is useful f
 You can accomplish this by creating a file called `preview-body.html` inside the Storybook config directory and add tags like this:
 
 ```html
-<div id="custom-root"></div>
+<div id="my-additional-root"></div>
 ```
 
 If using relative sizing in your project (like `rem` or `em`), you may update the base `font-size` by adding a `style` tag to `preview-body.html`: