Thank you @sguyader
It’s a good example of educational support, the result is very good 
Perhaps there are probably other ways to achieve (with RT) a similar result, if other volunteers wish to participate.
Overall from my point of view, Rawtherapee lacks educational materials, be it Rawpedia, videos, or documents of this type.
This supposes to have in addition to rawpedia and screenshot, adapted support (blog, page facebook, etc.)
Developers are generally not the right people to do this because they are focused on development, how to solve the problem and not how to concretely achieve a given result.
On the other hand, the developers - including me of course - are ready to contribute.
For example, I brought my advice to @XavAL for a complex module like “wavelet”, for a Spanish version of Rawpedia
Some modules are simple and the use almost obvious.
Others are complex, for example “Wavelet”, “Ciecam”, “Retinex”…or “Black and white”… or ??.
Others are not complex, but brings a mode treatment different from the habits, as for example “Local adjustemnts”
jacques