While I was reading the “Introduction to package management” I found several dead links. First this one regarding tutorials about the bash command https://aral.iut-rodez.fr/fr/sanchis/enseignement/bash/index.html and the link about app packaging https://forum.yunohost.org/c/apps-packaging then the link to github for submitting errors - therefore I am using the forum now https://github.com/yunohost/doc/blob/grav/pages/04.contribute/04.packaging_apps/packaging_apps_start.md
Apart from that, the other (working) bash tutorial link is French only.