Provide guidance on setting up TLS certificates when deploying Masakari. In particular, mention the relation to Vault. Improve admonishment concerning the choice of values for the `openstack-origin` and `series` settings. Use updated hardcoded values for series and OpenStack release. Remove redundant series information from the example overlay bundle. Closes-Bug: #1900019 Change-Id: I3e6c398f89c35f1719b7ebc33ea498ff54b96dcc