Update Time to First Byte (TTFB) link (vercel#33715)

The initial link was showing 404 not found



## 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`

docs/basic-features/data-fetching/get-server-side-props.md

@@ -33,7 +33,7 @@ The [`getServerSideProps` API reference](/docs/api-reference/data-fetching/get-s
 
 ## When should I use getServerSideProps
 
-You should use `getServerSideProps` only if you need to pre-render a page whose data must be fetched at request time. [Time to First Byte (TTFB)](/learn/seo/web-performance) will be higher than [`getStaticProps`](/docs/basic-features/data-fetching/get-static-props.md) because the server must compute the result on every request, and the result can only be cached by a CDN using `cache-control` headers (which could require extra configuration).
+You should use `getServerSideProps` only if you need to pre-render a page whose data must be fetched at request time. [Time to First Byte (TTFB)](https://web.dev/ttfb/) will be higher than [`getStaticProps`](/docs/basic-features/data-fetching/get-static-props.md) because the server must compute the result on every request, and the result can only be cached by a CDN using `cache-control` headers (which could require extra configuration).
 
 If you do not need to pre-render the data, then you should consider fetching data on the [client side](#fetching-data-on-the-client-side).