api-ref: remove encryption from Show-an-encryption-type
api-ref: remove encryption from Show-an-encryption-type

https://developer.openstack.org/api-ref/block-storage/v3/index.html#show-an-encryption-type
encryption is not a field in the response of "Show an encryption type",
this is to remove it.

Change-Id: Ie344e6f988cf71e97272910e84e0034ab8c317ff

mahak/cinder,openstack/cinder,openstack/cinder,mahak/cinder