Doc: fix broken link to api routes doc (#33836)

## Bug

- [ ] Related issues linked using `fixes #number`
- [ ] Integration tests added
- [ ] Errors have helpful link attached, see `contributing.md`

## Feature

- [ ] Implements an existing feature request or RFC. Make sure the feature request has been accepted for implementation before opening a PR.
- [ ] Related issues linked using `fixes #number`
- [ ] Integration tests added
- [ ] Documentation added
- [ ] Telemetry added. In case of a feature if it's used or not.
- [ ] Errors have helpful link attached, see `contributing.md`

## Documentation / Examples

- [ ] Make sure the linting passes by running `yarn lint`

examples/api-routes-graphql/README.md

@@ -1,6 +1,6 @@
 # API routes with GraphQL server
 
-Next.js ships with [API routes](https://github.com/vercel/next.js#api-routes), which provide an easy solution to build your own `API`. This example shows their usage alongside [apollo-server-micro](https://github.com/apollographql/apollo-server/tree/main/packages/apollo-server-micro) to provide simple GraphQL server consumed by Next.js app.
+Next.js ships with [API routes](https://nextjs.org/docs/api-routes/introduction), which provide an easy solution to build your own `API`. This example shows their usage alongside [apollo-server-micro](https://github.com/apollographql/apollo-server/tree/main/packages/apollo-server-micro) to provide simple GraphQL server consumed by Next.js app.
 
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