StyleGuide: Minor fix for themes.md (#56012)

* Update themes.md

* Update themes.md

* Updates

contribute/style-guides/themes.md

@@ -25,16 +25,16 @@ import { GrafanaTheme2 } from '@grafana/data';
 import { useStyles2 } from '@grafana/ui';
 import { css } from '@emotion/css';
 
-const getComponentStyles = (theme: GrafanaTheme2) => css`
-  padding: ${theme.spacing.md};
-`;
-
-const Foo: FC<FooProps> = () => {
-  const styles = useStyles2(getComponentsStyles);
+function Foo(props: FooProps) {
+  const styles = useStyles2(getStyles);
   // Use styles with className
-};
+}
 ```
 
+const getStyles = (theme: GrafanaTheme2) => css({
+padding: theme.spacing(1,2)
+});
+
 #### Get the theme object
 
 ```tsx