examples: update `with-sass` README.md (#73668)
## Summary
Follow up #73548.
Change `with-next-sass` to `with-sass` at Deploy your own section in
[README.md](https://github.com/vercel/next.js/blob/canary/examples/with-sass/README.md).
CC: @samcx
### Adding or Updating Examples
- [x] The "examples guidelines" are followed from our contributing doc
https://github.com/vercel/next.js/blob/canary/contributing/examples/adding-examples.md
- [x] Make sure the linting passes by running `pnpm build && pnpm lint`.
See
https://github.com/vercel/next.js/blob/canary/contributing/repository/linting.md
Co-authored-by: Sam Ko <sam@vercel.com>
