Add README around how to validate OSCAL

[aj-stein-nist]

Committer Notes

Follow on PR per discussion in #1153 to split high-level what is validation from how to validate. This is the latter. Per recs from @david-waltermire-nist, drop this in a README in the top-level dir of the project, and keep it separate from the core README.md. Together with #1169, this will closes #1153.

All Submissions:

• Have you selected the correct base branch per Contributing guidance?
• Have you checked to ensure there aren't other open Pull Requests for the same update/change?
• Have you squashed any non-relevant commits and commit messages? [instructions]
• Do all automated CI/CD checks pass?

Changes to Core Features:

• Have you added an explanation of what your changes do and why you'd like us to include them?
• Have you written new tests for your core changes, as applicable?
• Have you included examples of how to use your new feature(s)?
• Have you updated all OSCAL website and readme documentation affected by the changes you made? Changes to the OSCAL website can be made in the docs/content directory of your branch.

[david-waltermire]

Provided some feedback. This looks like a work in progress, so I did not approve or disapprove. Lots of links need to be added, but you have placeholders for most of these.

[aj-stein-nist]

Provided some feedback. This looks like a work in progress, so I did not approve or disapprove. Lots of links need to be added, but you have placeholders for most of these.

Nice, thanks for the feedback Dave, will be sure to work with Wendell more on it, but already wrapped in your suggestions (this this time using the batch feature of course!).

It took me a minute, but the batch feature requires you look at the PR from the files changed perspective or it breaks. That, or the add suggestion to batch button never works and you lose a few minutes of your sanity and life. :-)

[aj-stein-nist]

@david-waltermire-nist, sorry for the delays. This is ready for review. If you are happy with it, also read for inclusion to be released as part of v1.0.2 tomorrow.

[david-waltermire]

I requested some changes be made in the comments.

[aj-stein-nist]

As discussed yesterday afternoon, @david-waltermire-nist, gave one last past this morning before final ship. Caught some minor typos and touchups from shifting things on the call. I left the last commit so you can quickly see what I changed.

[wendellpiez]

@aj-stein-nist Arg I actually saw a couple of tinies, is there a way I can also touch up?

[aj-stein-nist]

@aj-stein-nist Arg I actually saw a couple of tinies, is there a way I can also touch up?

You can add suggestions like I do, explained in this tutorial video of I can walk you through it via Gitter, just message if this is hard to use and we can work through it.

[wendellpiez]

Offering a few touchups to wording here and there -- it looks nice!

[aj-stein-nist]

OK, @david-waltermire-nist, last typo fixes merged.

[david-waltermire]

Thanks for squashing and for this work!