chore: tweak sidebar story text

addons/rose/addon/components/rose/layout/sidebar.stories.mdx

@@ -8,7 +8,7 @@ import { text, boolean, select } from '@storybook/addon-knobs';
 # Layout|Sidebar
 
 A top-level layout/positioning component that allows two distinct sections to
-be configured: header and body.
+be configured: sidebar and body.
 
 ```htmlbars
 <Rose::Layout::Sidebar as |layout|>