docs: split icon attribute in a new sentence

Co-authored-by: Chris Swithinbank <swithinbank@gmail.com>

docs/src/content/docs/guides/components.mdx

@@ -58,7 +58,8 @@ These components are available from the `@astrojs/starlight/components` package.
 import { Tabs, TabItem } from '@astrojs/starlight/components';
 
 You can display a tabbed interface using the `<Tabs>` and `<TabItem>` components.
-Each `<TabItem>` must have a `label` to display to users and can optionally include an `icon` attribute set to the name of [one of Starlight’s built-in icons](#all-icons).
+Each `<TabItem>` must have a `label` to display to users.
+Use the optional `icon` attribute to include one of [Starlight’s built-in icons](#all-icons) next to the label.
 
 ```mdx
 # src/content/docs/example.mdx