Add instructions to destroy the local instance

Hi @apellecc, thank you for the merge request. I would suggest to also mention it is preferable to Halt the FSM of configuration to be destroyed first. Failing to do so does not allow the TCDS lease to be released. It can (and did) lead to problems if another configuration is instantiated too early. In such cases, simply waiting (about 30 seconds) recovers the situation as the TCDS lease eventually expires.