Undeprecate options used for signing
Undeprecate options used for signing

The options were deprecated when PKI was deprecated. However, they are
used not only for PKI. Revocation lists API uses it too. We cannot
remove API without major version bump. Because of that, we have to stick
with them.

Undeprecate options used for signing. Remove mentions of PKI and
describe that they are now used for signing responses of revocation
lists API.

Change-Id: Ib0e194fbafe83c467381283b555868a1fb02a512

mahak/keystone,openstack/keystone,ilay09/keystone,rajalokan/keystone,rajalokan/keystone,rajalokan/keystone,ilay09/keystone,openstack/keystone,ilay09/keystone,mahak/keystone,openstack/keystone,mahak/keystone