📝 Update release notes

Author: tiangolo

docs/en/docs/release-notes.md

@@ -9,6 +9,7 @@
 
 ### Docs
 
+* Add link to the course by TestDriven.io: [Test-Driven Development with FastAPI and Docker](https://testdriven.io/courses/tdd-fastapi/). PR [#1860](https://github.com/tiangolo/fastapi/pull/1860).
 * Fix empty log message in docs example about handling errors. PR [#1815](https://github.com/tiangolo/fastapi/pull/1815) by [@manlix](https://github.com/manlix).
 * Reword text to reduce ambiguity while not being gender-specific. PR [#1824](https://github.com/tiangolo/fastapi/pull/1824) by [@Mause](https://github.com/Mause).