[log] Add file hierarchy for hardware intervention logs

log/grid5000/sites/grenoble/clusters/drac/nodes/drac-6.md

log/grid5000/sites/grenoble/clusters/drac/nodes/drac-7.md

log/grid5000/sites/grenoble/clusters/drac/nodes/drac-8.md

log/grid5000/sites/grenoble/clusters/drac/nodes/drac-9.md

...grid5000/sites/grenoble/clusters/servan/nodes/servan-1.md

...grid5000/sites/grenoble/clusters/servan/nodes/servan-2.md

log/grid5000/sites/grenoble/clusters/troll/nodes/troll-1.md

log/grid5000/sites/grenoble/clusters/troll/nodes/troll-2.md

log/grid5000/sites/grenoble/clusters/troll/nodes/troll-3.md

log/grid5000/sites/grenoble/clusters/troll/nodes/troll-4.md

log/grid5000/sites/grenoble/clusters/yeti/nodes/yeti-1.md

log/grid5000/sites/grenoble/clusters/yeti/nodes/yeti-2.md

log/grid5000/sites/grenoble/clusters/yeti/nodes/yeti-3.md

log/grid5000/sites/grenoble/clusters/yeti/nodes/yeti-4.md

log/grid5000/sites/lille/clusters/chiclet/nodes/chiclet-1.md

log/grid5000/sites/lille/clusters/chiclet/nodes/chiclet-2.md

log/grid5000/sites/lille/clusters/chiclet/nodes/chiclet-3.md

log/grid5000/sites/lille/clusters/chiclet/nodes/chiclet-4.md

log/grid5000/sites/lille/clusters/chiclet/nodes/chiclet-5.md

log/grid5000/sites/lille/clusters/chiclet/nodes/chiclet-6.md