馃帹 Reordered text and improved readme
This MR includes text reordering following the Metalab documentation template here : https://gitlab.com/sat-metalab/documentations/templates/-/blob/master/doc_model_0/README.md
Lower level document as been moved to specific md files: install from sources, monitoring shmdata framerate and packaging.
Docker documentation was not up to date and has been removed.