docs: fix route matcher in brands guide (medusajs#12741)

Author: shahednasser

www/apps/book/app/learn/customization/custom-features/api-route/page.mdx

@@ -157,7 +157,7 @@ You define the middlewares using the `defineMiddlewares` function and export its
 
 In the middleware object, you define three properties:
 
-- `matcher`: a string or regular expression indicating the API route path to apply the middleware on. You pass the create brand's route `/admin/brand`.
+- `matcher`: a string or regular expression indicating the API route path to apply the middleware on. You pass the create brand's route `/admin/brands`.
 - `method`: The HTTP method to restrict the middleware to, which is `POST`.
 - `middlewares`: An array of middlewares to apply on the route. You pass the `validateAndTransformBody` middleware, passing it the Zod schema you created earlier.