docs(nextjs): Mention the deferred pageload start in the changelog entry

Co-Authored-By: Claude Fable 5.1 <noreply@anthropic.com>

Author: chargome

CHANGELOG.md

@@ -6,7 +6,7 @@
 
 - **feat(nextjs): Never emit trace meta tags from a prerender ([#25141](https://github.com/getsentry/sentry-javascript/pull/25141))**
 
-  Apps with `cacheComponents` enabled get the `sentry-trace` and `baggage` meta tags again, so a pageload joins the trace of the server request that rendered the page. The server SDK no longer writes these tags while Next.js prerenders a page, so a cached shell never carries the trace of another visitor. This also covers ISR pages, which no longer need the client-side removal of the tags.
+  Apps with `cacheComponents` enabled get the `sentry-trace` and `baggage` meta tags again, so a pageload joins the trace of the server request that rendered the page. The server SDK no longer writes these tags while Next.js prerenders a page, so a cached shell never carries the trace of another visitor. This also covers ISR pages, which no longer need the client-side removal of the tags. When the tags arrive with the part of the page that streams in after a cached shell, the pageload span is created once they have arrived, with its start still at the time origin.
 
 Work in this release was contributed by @Philip-Nwabuwa and @4ktLuffy. Thank you for your contributions!