Update data format tutorial with a real image

[guillaumeeb]

See #3 (review).

Thanks for this tutorial : it's simple and well explained. But maybe it would be interesting to leave user try with a bigger image, because with such size of images, it's hard to see differences.
Could you at least mention the read time and the size of a much bigger image (such as a full S2 product ?) ?

Thank you for your feedback. I used this image because it could be automatically downloaded with a script. I couldn't find a full S2 image available for download without requiring an account on a provider’s website, which would have added complexity to the tutorial. Additionally, such an image would be too large to host directly in the repo.

I can add a subsection with read/write times and file sizes for all formats based on my tests I did with a real S2 image. I'll then include a short paragraph inviting users to download data from a provider and running the same benchmarks.

I have public S2 images available here: gs://supaero/31TCH/