[strasbourg][engelbourg] Update first description of engelbourg cluster

...5000/sites/strasbourg/clusters/engelbourg/engelbourg.json

...es/strasbourg/clusters/engelbourg/nodes/engelbourg-1.json

...es/strasbourg/clusters/engelbourg/nodes/engelbourg-2.json

...es/strasbourg/clusters/engelbourg/nodes/engelbourg-3.json

...es/strasbourg/clusters/engelbourg/nodes/engelbourg-4.json

...es/strasbourg/clusters/engelbourg/nodes/engelbourg-5.json

...es/strasbourg/clusters/engelbourg/nodes/engelbourg-6.json

...es/strasbourg/clusters/engelbourg/nodes/engelbourg-7.json

...es/strasbourg/clusters/engelbourg/nodes/engelbourg-8.json

input/grid5000/ipv4.yaml

...5000/sites/strasbourg/clusters/engelbourg/engelbourg.yaml

...d5000/sites/strasbourg/clusters/engelbourg/nodes.yaml.erb