[nancy][grdix-srv] add group storage rates/data

data/grid5000/sites/nancy/servers/grdix-srv.json

@@ -2,6 +2,11 @@
   "alias": [
     "storage6"
   ],
+  "group_storage": {
+    "name": "storage6",
+    "rate": 25000000000,
+    "size": 86000000000000
+  },
   "kind": "physical",
   "network_adapters": {
     "bmc": {