Update demo-deploy-on-g5k.md

demo-deploy-on-g5k.md

 # Deploy a bare-metal on G5k in n steps
 
+## Connected to nantes site 
+
+- direct way through a proxy
+```bash
+ssh nantes.g5k
+```
+or 
+
+- go the frontal node 
+```bash
+ssh access.grid5000.fr 
+ssh nantes
+```
+
 ## Prepare the node to be deployed
 
 ```bash