chore: add comment to example ssh key

examples/create_and_ssh_into_a_server.md

@@ -12,7 +12,7 @@ In order to be able to connect to the server we are going to create, we will nee
 
 ```sh
 # Create ssh-key into current working directory
-ssh-keygen -t ed25519 -q -f "./id_ed25519" -N ""
+ssh-keygen -t ed25519 -q -f "./id_ed25519" -N "" -C "upctl example"
 ```
 
 Create a server using the above created ssh-key as login method.