docs(www): update manual.mdx (#1471)

Fix file name

Co-authored-by: shadcn <m@shadcn.com>

apps/www/content/docs/installation/manual.mdx

@@ -139,7 +139,7 @@ module.exports = {
 
 Add the following to your styles/globals.css file. You can learn more about using CSS variables for theming in the [theming section](/docs/theming).
 
-```css title="styles.css"
+```css title="globals.css"
 @tailwind base;
 @tailwind components;
 @tailwind utilities;