Add Fran's testimonial

Signed-off-by: Juan Cruz Viotti <jv@jviotti.com>

Author: jviotti

content/courses/jsonschema-for-openapi/_index.html

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+        {{< testimonial github="fmvilas" name="Fran Mendez" role="Creator of AsyncAPI" >}}When I think of JSON Schema experts, Juan is one of the very first names that comes to mind. He doesn't just understand the spec inside and out. He's actively building amazing, practical tools that make working with JSON Schema so much better for everyone. His work is a huge asset to the community.{{< /testimonial >}}
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         {{< testimonial github="ronitelman" name="Ron Itelman" role="Founder, TrustLoop" >}}Juan Cruz Viotti has an exceptionally deep understanding of JSON Schema and how to leverage it to solve real-world problems. His course provides tremendous value for organizations looking to train their teams on operationalizing JSON Schemas for API design, data validation, and model definition. His practical approach goes beyond theory to show how JSON Schema can become a core part of your technical infrastructure.{{< /testimonial >}}
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         {{< testimonial github="bavulapati" name="Bala Avulapati" role="Author of AJV-Plus" >}}Taking Juan's course on JSON Schema for OpenAPI was truly enlightening. He brings an unmatched depth of knowledge to the table. His firsthand experience developing and evolving the JSON Schema ecosystem makes his teaching uniquely practical and insightful. A must-take for anyone serious about mastering JSON Schema in modern API development.{{< /testimonial >}}
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         {{< testimonial github="thundron" name="Lorenzo Ambrosi" role="Founder, Axeleron Tech" >}}I have been using JSON Schema without even realizing it sometimes. Juan's teachings really helped me take a step forward in actually understanding the specs for real-world use-cases that I had not thought of, even though I stumble across them pretty much daily!{{< /testimonial >}}
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