This patch updates the overview_encryption page to add a
`Changing the encryption root secret of external KMS's` section
to point out the slight difference in naming. I.E:
key_id_<secret_id> vs. encryption_root_secret_<secret_id>
This patch refers to both multikey support in the KMIP and KMS
key masters, so really should land after both of them.
Related-Change-Id: Ie52508e47d15ec5c4e96902d3c9f5f282d275683
Related-Change-Id: I4f485dcb31e5bea511c4e539c54681091fc5bb1c
Change-Id: Ie4cd8ae038501c8abc43d09cf0b207ca375a4366