Update upgrade-guide.mdx (#2036)

Author: martinoak

src/docs/upgrade-guide.mdx

@@ -383,7 +383,7 @@ To customize the `container` utility in v4, extend it using the `@utility` direc
 
 In v3, the `border-*` and `divide-*` utilities used your configured `gray-200` color by default. We've changed this to `currentColor` in v4 to make Tailwind less opinionated and match browser defaults.
 
-To update your project for this change, make sure you specify a color anywhere you're using a `border-*` or `divide-*` utility utility:
+To update your project for this change, make sure you specify a color anywhere you're using a `border-*` or `divide-*` utility:
 
 ```html
 <!-- [!code classes:border-gray-200] -->