docs: update usePrefix.ts reference (#18119)

Signed-off-by: Emmanuel Ferdman <emmanuelferdman@gmail.com>

Author: emmanuel-ferdman

packages/react/src/internal/usePrefix.mdx

@@ -6,7 +6,7 @@ import { usePrefix } from './usePrefix';
 
 # usePrefix
 
-[Source code](https://github.com/carbon-design-system/carbon/blob/main/packages/react/src/internal/usePrefix.js)
+[Source code](https://github.com/carbon-design-system/carbon/blob/main/packages/react/src/internal/usePrefix.ts)
 
 ## Overview