📝 Update release notes

docs/en/docs/release-notes.md

@@ -2,6 +2,7 @@
 
 ## Latest Changes
 
+* 🔧 Swap light/dark theme button icon. PR [#3246](https://github.com/tiangolo/fastapi/pull/3246) by [@eddsalkield](https://github.com/eddsalkield).
 * 📝 Add external link to article: How-to deploy FastAPI app to Heroku. PR [#3241](https://github.com/tiangolo/fastapi/pull/3241) by [@Jarmos-san](https://github.com/Jarmos-san).
 * ✏ Fix link in Japanese docs for `docs/ja/docs/deployment/docker.md`. PR [#3245](https://github.com/tiangolo/fastapi/pull/3245) by [@utamori](https://github.com/utamori).
 * ✏ Fix typo (mistranslation) in `docs/en/docs/advanced/templates.md`. PR [#3211](https://github.com/tiangolo/fastapi/pull/3211) by [@oerpli](https://github.com/oerpli).