[chore] [editoral] switch to md front matter

[thompson-tomo]

Fixes #1976

Progresses #1821

Changes

This switches to github front matter syntax to enable

This also enables the first line h1 check to be turned on.

Question's:

• Do we need to keep # Hugo front matter used to generate the website version of this page? Or can it be removed?

Important

Pull requests acceptance are subject to the triage process as described in Issue and PR Triage Management.
PRs that do not follow the guidance above, may be automatically rejected and closed.

Merge requirement checklist

• CONTRIBUTING.md guidelines followed.
• Change log entry added, according to the guidelines in When to add a changelog entry.
  • If your PR does not need a change log, start the PR title with [chore]
• Links to the prototypes or existing instrumentations (when adding or changing conventions)

[thompson-tomo]

Build issue due to current toc generator having known issues with front matter syntax & isn't mantained. Will need to be addressed by switching to https://www.npmjs.com/package/doctoc