Document that Google has begun using CLS metric (#27843)

Google has begun using Cumulative Layout Shift as a factor in ranking search results, according to the linked Google docs.

This perhaps will make this page out of sync with other Nextjs docs, but I figure better start somewhere.



## Bug

- [ ] Related issues linked using `fixes #number`
- [ ] Integration tests added
- [x] 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

docs/basic-features/image-optimization.md

@@ -23,7 +23,7 @@ Instead of optimizing images at build time, Next.js optimizes images on-demand,
 
 Images are lazy loaded by default. That means your page speed isn't penalized for images outside the viewport. Images load as they are scrolled into viewport.
 
-Images are always rendered in such a way as to avoid [Cumulative Layout Shift](https://web.dev/cls/), a [Core Web Vital](https://web.dev/vitals/) that Google is going to [use in search ranking](https://webmasters.googleblog.com/2020/05/evaluating-page-experience.html).
+Images are always rendered in such a way as to avoid [Cumulative Layout Shift](https://web.dev/cls/), a [Core Web Vital](https://web.dev/vitals/) that Google [uses in search ranking](https://developers.google.com/search/blog/2020/05/evaluating-page-experience).
 
 ## Image Component