📝 Add link to TestDriven.io course in docs (#1860)

Author: tiangolo

docs/en/docs/advanced/index.md

@@ -16,3 +16,9 @@ In the next sections you will see other options, configurations, and additional
 You could still use most of the features in **FastAPI** with the knowledge from the main [Tutorial - User Guide](../tutorial/){.internal-link target=_blank}.
 
 And the next sections assume you already read it, and assume that you know those main ideas.
+
+## TestDriven.io course
+
+If you would like to take an advanced-beginner course to complement this section of the docs, you might want to check: <a href="https://testdriven.io/courses/tdd-fastapi/" class="external-link" target="_blank">Test-Driven Development with FastAPI and Docker</a> by **TestDriven.io**.
+
+They are currently donating 10% of all profits to the development of **FastAPI**. 🎉 😄