Install Instructions for building the source

[GanbaruTobi]

Feature Request

Is your feature request related to a problem? Please describe.
I want to build from source instead of using pip. But there are missing informations and the build fails.

Describe the solution you'd like
Clear instructions on how to replicate a functioning build from source in the readme or in an Install.md

[arthaud]

Build from source instructions are here: https://mariana-tren.ch/docs/contribution/

If the build still fail, could you please send use your logs?