Link to OpenAPI video course in the README

Signed-off-by: Juan Cruz Viotti <[email protected]>

Author: jviotti

README.markdown

@@ -18,13 +18,13 @@ catalogs with enterprise-grade governance capabilities.
 - **[:briefcase: Commercial Licensing](https://registry.sourcemeta.com/commercial)** - Enterprise support
 - **[:speech_balloon: Community Support](https://github.com/sourcemeta/registry/discussions)** - GitHub Discussions
 
-> Do you want to level up your JSON Schema skills? Check out
+> [!TIP] Do you want to level up your JSON Schema skills? Check out
 > [learnjsonschema.com](https://www.learnjsonschema.com), our growing JSON
-> Schema documentation website, our O'Reilly book [Unifying Business, Data, and
-> Code: Designing Data Products with JSON
-> Schema](https://www.oreilly.com/library/view/unifying-business-data/9781098144999/),
-> and our popular open-source [JSON Schema
-> CLI](https://github.com/sourcemeta/jsonschema).
+> Schema documentation website, our [JSON Schema for
+> OpenAPI](https://www.sourcemeta.com/courses/jsonschema-for-openapi) video
+> course, and our O'Reilly book [Unifying Business, Data, and Code: Designing
+> Data Products with JSON
+> Schema](https://www.oreilly.com/library/view/unifying-business-data/9781098144999/).
 
 ## :page_facing_up: License