(EPIC) OSCAL and Metaschema cleanup and declutter

[wendellpiez]

User Story:

As an OSCAL developer and user, I need the OSCAL repository to be orderly, intelligible, documented accurately and comprehensively, and consistent.

Goals:

The OSCAL repository needs to be comfortable and welcoming to visitors. This means not a lot of confusion, loose and unexplained resources, or out of date readmes.

This applies to the Metaschema and other OSCAL-related repositories as well. See usnistgov/metaschema#164.

Dependencies:

None currently.

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.}

[wendellpiez]

Notes on OSCAL repo cleanup (see WIP branch at https://github.com/wendellpiez/oscal/tree/issue966-defenestration-jun2021):

• build\metaschema - metaschema submodule cf Wanting a clean easy-to-use repository metaschema#164
• content - all autopopulated (?)
• docs - Hugo installation
• json - all autopopulated
• xml - ditto
• src ...
  • Leaving specifications for later
  • Leaving release
  • content directory - ? (only has a copy of oldish SP800-53 source)
  • utils/schematron - keep but clean up / readme
  • utils/author/CSS - moved to oscal-tools
  • inside utils: removed convert, publish and lib
  • utils/util/resolver-experimental - moved elsewhere until I can return

[wendellpiez]

Now done, for now (always more)