📝 Update release notes

[skip ci]

Author: github-actions[bot]

docs/en/docs/release-notes.md

@@ -12,6 +12,10 @@ hide:
 * ✨ Show a clear error on attempt to include router into itself. PR [#14258](https://github.com/fastapi/fastapi/pull/14258) by [@JavierSanchezCastro](https://github.com/JavierSanchezCastro).
 * ✨ Replace `dict` by `Mapping` on `HTTPException.headers`. PR [#12997](https://github.com/fastapi/fastapi/pull/12997) by [@rijenkii](https://github.com/rijenkii).
 
+### Refactors
+
+* ♻️ Simplify reading files in memory, do it sequentially instead of (fake) parallel. PR [#14884](https://github.com/fastapi/fastapi/pull/14884) by [@tiangolo](https://github.com/tiangolo).
+
 ### Internal
 
 * 🔧 Configure `test` workflow to run tests with `inline-snapshot=review`. PR [#14876](https://github.com/fastapi/fastapi/pull/14876) by [@YuriiMotov](https://github.com/YuriiMotov).