Improve instructions to build Pallas and eztrace
- precise how to install dependencies
- fix cmake command for eztrace to add missing OTF2_ROOT
- add how to check if eztrace was successfuly built
[A venir] Mise en place de quotas sur nos instances GitLab. Plus d'information sur : https://doc-si.inria.fr/pages/viewpage.action?pageId=129728565
[Coming soon] Quotas installation on our GitLab instances. More information: https://doc-si.inria.fr/pages/viewpage.action?pageId=129728565