message: docs: update features section
diff: @@ -84,7 +84,8 @@ Is there a feature that you want but is not yet supported? Please open a [new is
  - [x] [Redirects](https://nextjs.org/docs/api-reference/next.config.js/redirects). In latest alpha release (caveat: every route should be able to redirect except `_next/static/*` and `static/*`, since those cache behaviors do not have Lambda handlers attached to them). See [RFC](https://github.com/serverless-nextjs/serverless-next.js/issues/587) for updates.
  - [x] [Rewrites](https://nextjs.org/docs/api-reference/next.config.js/rewrites). In latest alpha release (caveats: every route should be able to rewrite except `_next/static/*` and `static/*`, since those cache behaviors do not have Lambda handlers attached to them. [External URL rewrites](https://nextjs.org/docs/api-reference/next.config.js/rewrites#rewriting-to-an-external-url) are not yet implemented). See [RFC](https://github.com/serverless-nextjs/serverless-next.js/issues/587) for updates.
  - [x] [Custom Headers](https://nextjs.org/docs/api-reference/next.config.js/headers). In latest alpha release (caveats: every route should be able to have custom headers except `_next/static/*` and `static/*`, since those cache behaviors do not have Lambda handlers attached to them. You also need to specify the S3 key as the source when redirecting any path mapped to an S3 file (see [PR](https://github.com/serverless-nextjs/serverless-next.js/pull/662) for more details). See [RFC](https://github.com/serverless-nextjs/serverless-next.js/issues/587) for updates.
  -- [ ] [Next.js 10 Features](https://nextjs.org/blog/next-10). A few issues such as https://github.com/serverless-nextjs/serverless-next.js/issues/725 and https://github.com/serverless-nextjs/serverless-next.js/issues/721 are in progress, aiming for 1.19 release.
  +- [x] [Image Optimization](https://nextjs.org/docs/basic-features/image-optimization) Available in the latest 1.19 alpha version. Please try it out and let us know if there are any bugs.
  +- [ ] [Next.js 10 Features](https://nextjs.org/blog/next-10). A few issues such as https://github.com/serverless-nextjs/serverless-next.js/issues/721 are in progress, aiming for 1.19 release.
  ### Getting started
  