[Backport 5.0] changelog update (#50840)

Was in the wrong place, so just moving it.
## Test plan

changelog update <br> Backport 4c215a2
from #50830

---------

Co-authored-by: Idan Varsano <[email protected]>

Author: github-actions[bot]

CHANGELOG.md

@@ -46,6 +46,7 @@ All notable changes to Sourcegraph are documented in this file.
 - For Cody, explicitly detect some cases where context is needed to avoid failed responses. [#50541](https://github.com/sourcegraph/sourcegraph/pull/50541)
 - Code Insights that are run over zero repositories will finish processing and show `"No data to display"`. #[50561](https://github.com/sourcegraph/sourcegraph/pull/50561)
 - DNS timeouts on calls to host.docker.internal from every html page load for docker-compose air-gapped instances. No more DNS lookups in jscontext.go anymore. #[50638](https://github.com/sourcegraph/sourcegraph/pull/50638)
+- Improved the speed of the embedding index by significantly decreasing the calls to Gitserver. [#50410](https://github.com/sourcegraph/sourcegraph/pull/50410)
 
 ### Removed