📝 Update release notes

docs/en/docs/release-notes.md

@@ -2,6 +2,7 @@
 
 ## Latest changes
 
+* Allow disabling docs UIs by just disabling OpenAPI with `openapi_url=None`. New example in docs: [Advanced: Conditional OpenAPI](https://fastapi.tiangolo.com/advanced/conditional-openapi/). PR [#1421](https://github.com/tiangolo/fastapi/pull/1421).
 * Add translation to Portuguese for [Benchmarks - Comparações](https://fastapi.tiangolo.com/pt/benchmarks/). PR [#1274](https://github.com/tiangolo/fastapi/pull/1274) by [@Serrones](https://github.com/Serrones).
 * Add translation to Portuguese for [Tutorial - User Guide - Intro - Tutorial - Guia de Usuário - Introdução](https://fastapi.tiangolo.com/pt/tutorial/). PR [#1259](https://github.com/tiangolo/fastapi/pull/1259) by [@marcosmmb](https://github.com/marcosmmb).
 * Allow using Unicode in MkDocs for translations. PR [#1419](https://github.com/tiangolo/fastapi/pull/1419).