doc: Volume encryption supported by the key manager in cinder

[Eric Harney]

- [X] This doc is inaccurate in this way: ______

"Initial configuration" states that cinder-api needs to be restarted, but cinder-volume and cinder-backup also need to be restarted.

-----------------------------------
Release: 18.1.0.dev102 on 2021-03-24 04:49:45
SHA: 47c2d660e28bf5ca6b4c5d8c008d50ed83a65de3
Source: https://opendev.org/openstack/cinder/src/doc/source/configuration/block-storage/volume-encryption.rst
URL: https://docs.openstack.org/cinder/latest/configuration/block-storage/volume-encryption.html

[Sofia Enriquez (lsofia-enriquez)]

Fix proposed https://review.opendev.org/c/openstack/cinder/+/792638

[OpenStack Infra (hudson-openstack)]

Fix proposed to branch: master
Review: https://review.opendev.org/c/openstack/cinder/+/818233

[OpenStack Infra (hudson-openstack)]

Reviewed: https://review.opendev.org/c/openstack/cinder/+/818233
Committed: https://opendev.org/openstack/cinder/commit/6904db860544340a9e7d4a0aa0382f792f518aa9
Submitter: "Zuul (22348)"
Branch: master

commit 6904db860544340a9e7d4a0aa0382f792f518aa9
Author: LeoCampelo <email address hidden>
Date: Wed Nov 17 11:09:36 2021 -0300

    DOC: Add cinder modules on initial configuration

    Added cinder-volume and cinder-backup to be restarted as well as
    cinder-api in block storage encryption initial configuration.

    Closes-Bug: 1929220
    Change-Id: I5b26e28478e6f7061077886304f9cebf481ff55f

[OpenStack Infra (hudson-openstack)]

This issue was fixed in the openstack/cinder 20.0.0.0rc1 release candidate.