Update example KES config in helm chart (#2008)

Update example KES config

* Starting KES version `2023-11-10T10-44-28Z` the `keys` was renamed to `keystore`.
* Using default entity as `admin` instead of apply a policy, as a best-practice recommended.
* `root` field no longer exists

Signed-off-by: pjuarezd <pjuarezd@users.noreply.github.com>

Author: pjuarezd

helm/tenant/values.yaml

@@ -348,30 +348,23 @@ tenant:
   #  replicas: 2
   #  configuration: |-
   #    address: :7373
-  #    root: _ # Effectively disabled since no root identity necessary.
   #    tls:
   #      key: /tmp/kes/server.key   # Path to the TLS private key
   #      cert: /tmp/kes/server.crt # Path to the TLS certificate
   #      proxy:
   #        identities: []
   #        header:
   #          cert: X-Tls-Client-Cert
-  #    policy:
-  #      my-policy:
-  #        paths:
-  #        - /v1/key/create/*
-  #        - /v1/key/generate/*
-  #        - /v1/key/decrypt/*
-  #        identities:
-  #        - ${MINIO_KES_IDENTITY}
+  #    admin:
+  #      identity: ${MINIO_KES_IDENTITY}
   #    cache:
   #      expiry:
   #        any: 5m0s
   #        unused: 20s
   #    log:
   #      error: on
   #      audit: off
-  #    keys:
+  #    keystore:
   #      # KES configured with fs (File System mode) doesn't work in Kubernetes environments and is not recommended
   #      # use a real KMS
   #      # fs: