Add info about jsdoc on Project Structure

[ericdiviney]

It is possible to write typescript using only JSDOC. I am not famiiar with the approach, but we should at least mention that on the page where we also suggest jsdoc. I wasn't even aware, and it is a different way that teams can ensure type-safety.

https://www.prisma.io/blog/type-safe-js-with-jsdoc-typeSaf3js