Add support for document revision histories

[david-waltermire]

User Story:

As an OSCAL content creator, I need a way to provide a document revision history.

Goals:

Add support for a revision history in the document metadata.

Dependencies:

None.

Acceptance Criteria

• All OSCAL website and readme documentation affected by the changes in this issue have been updated. Changes to the OSCAL website can be made in the docs/content directory of your branch.
• A Pull Request (PR) is submitted that fully addresses the goals of this User Story. This issue is referenced in the PR.
• The CI-CD build process runs without any reported errors on the PR. This can be confirmed by reviewing that all checks have passed in the PR.

{The items above are general acceptance criteria for all User Stories. Please describe anything else that must be completed for this issue to be considered resolved.}

[david-waltermire]

The following are notes from a previous discussion.

Current state:

metadata:
  published: date : date the OSCAL instance was published
  last-modified: date : date the OSCAL instance was last modified
  version: string : version of the OSCAL instance

Future state:

metadata:
  revision-history: revision history of the OSCAL document based on feedback from #498
  published: date : date the OSCAL instance was published
  last-modified: date : date the OSCAL instance was last modified
  version: string : version of the OSCAL instance
  link: rel="source" href="#pointer": pointer to a resource indicating the source the OSCAL instance was derived from
back-matter:
  resources/citations:
    resource/citation:
      id: used for the source pointer above
      properties:
        prop:
          name: published
          value: date

• merge citation into resource
  • add title and document-ids
  • add "accessed-on: date"
  • review FedRAMP extensions

[bradh]

+1 on revision history as a need.

Side note: rel="source" doesn't appear in https://www.iana.org/assignments/link-relations/link-relations.xhtml. I thought perhaps derivedFrom.

[brian-ruf]

Added separate issue #612 for the merging of citation into resource.

[david-waltermire]

This issue was also referenced in #498. Here is the specific design in pseudo-YAML from that issue:

versions:
  version:
    published: 
    last-modified: 
    version: 
    oscal-version: 1.0
    uri: over links for uniqueid href and integrity

[brian-ruf]

30-Jan-2020 Status

@david-waltermire-nist implemented changes in the metaschema to support this. Those changes are in his branch and require a PR.

[david-waltermire]

This is addressed by PR #619.