Update doc

Update:

• logo update
• add jupyterhub link (documentation frontpage, index.md)
• fix broken links
• update cluster description (storage)
• add IFB ressources limits (slurm_at_ifb.md page)
• fix account creation information (use MY instead of sending an email)
• remove certificats provider name (security.md page)
• fix syntax (project.md page)
• add project information on data.md page