feat(daffio): create doc heading component

[xelaint]

PR Checklist

Please check if your PR fulfills the following requirements:

• The commit message follows our guidelines: https://github.com/graycoreio/daffodil/blob/develop/CONTRIBUTING.md#commit
• Tests for the changes have been added (for bug fixes / features)
• Docs have been added / updated (for bug fixes / features)

PR Type

What kind of change does this PR introduce?

[ ] Bugfix
[x] Feature
[ ] Code style update (formatting, local variables)
[ ] Refactoring (no functional changes, no api changes)
[ ] Build related changes
[ ] CI related changes
[ ] Documentation content changes
[ ] Other... Please describe:

What is the current behavior?

Fixes: #3895, fixes: #3893, fixes: #3894

What is the new behavior?

Does this PR introduce a breaking change?

[ ] Yes
[x] No

Other information

[xelaint]

@griest024 should this also be added to readme headings too? (e.g. design component docs, guides docs)

[griest024]

@griest024 should this also be added to readme headings too? (e.g. design component docs, guides docs)

Yes but those are markdown rendered and so it's more complicated to do so. We could expose the heading component as a custom element and then customize the markdown rendering of headings.

[xelaint]

@griest024 should this also be added to readme headings too? (e.g. design component docs, guides docs)

Yes but those are markdown rendered and so it's more complicated to do so. We could expose the heading component as a custom element and then customize the markdown rendering of headings.

Do you want to do this in a separate PR?

[griest024]

@griest024 should this also be added to readme headings too? (e.g. design component docs, guides docs)

Yes but those are markdown rendered and so it's more complicated to do so. We could expose the heading component as a custom element and then customize the markdown rendering of headings.

Do you want to do this in a separate PR?

Yeah I think so. Custom elements opens a can of worms