* docs/vault-k8s: add overview for consul template fetches
* Add dynamic role link
* move to agent documentation, add link
* fix typo in certificate doc
* fix note about leased secrets
* update secret vs token, add note to pki
* add more secret vs token notes
* add note about caching
For situations where you want the Vault agent to handle one or more templates but do not require the acquired credentials elsewhere.
Modify the logic in SyncServer so that if there are no sinks, ignore any new credentials. Since SyncServer is responsible for shutting down the agent, make sure it still properly shuts down in this new situation.
Solves #7988
