the julialang page suggests to install juliaup. we should be consistent here: https://sienna-platform.github.io/Sienna/SiennaDocs/docs/build/how-to/install/#install
the julialang page suggests to install juliaup. we should be consistent here: https://sienna-platform.github.io/Sienna/SiennaDocs/docs/build/how-to/install/#install