Update release container info

Update release container info

- Update schema to require pull and push container
registries
  - This will fix issues where for example ONAP pulls from
    snapshots exclusively where other projects like O-RAN
    use both snapshots or staging.
  - Allows for future push to DockerHub
  - Benefits projects like O-RAN and Acumos where they already
    provide this information for other docker jobs.
  - Pull and push registries need to be defined as Jenkins
    global variables.
  - Can be overwritten in releases files.
- Update some echos to allow users to find information faster.

Change-Id: Ibd0088c6419bacca16ded4ae86d70304c5bad45c
Signed-off-by: Jessica Wagantall <jwagantall@linuxfoundation.org>