docs: fix the link to another document (vercel#53599)

The link used to be "https://github.com/acdlite/rfcs/blob/first-class-promises/text/0000-first-class-support-for-promises" but actually "https://github.com/acdlite/rfcs/blob/first-class-promises/text/0000-first-class-support-for-promises.md" is correct (needs ".md" at the end)

docs/02-app/01-building-your-application/02-data-fetching/01-fetching-caching-and-revalidating.mdx

@@ -16,7 +16,7 @@ There are three main ways you can fetch data:
 
 Next.js extends the native [`fetch` Web API](https://developer.mozilla.org/en-US/docs/Web/API/Fetch_API) to allow you to configure the [caching](#caching-data) and [revalidating](#revalidating-data) behavior for each fetch request on the server. React extends `fetch` to automatically [memoize](/docs/app/building-your-application/data-fetching/patterns#fetching-data-where-its-needed) fetch requests while rendering a React component tree.
 
-You can use `fetch` with [`async`/`await` in Server Components](https://github.com/acdlite/rfcs/blob/first-class-promises/text/0000-first-class-support-for-promises), in [Route Handlers](/docs/app/building-your-application/routing/route-handlers), and in [Server Actions](/docs/app/building-your-application/data-fetching/server-actions).
+You can use `fetch` with [`async`/`await` in Server Components](https://github.com/acdlite/rfcs/blob/first-class-promises/text/0000-first-class-support-for-promises.md), in [Route Handlers](/docs/app/building-your-application/routing/route-handlers), and in [Server Actions](/docs/app/building-your-application/data-fetching/server-actions).
 
 For example: