fix(design): update links in design package markdowns to absolute paths

[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?

[x] Bugfix
[ ] 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: #2815

What is the new behavior?

Does this PR introduce a breaking change?

[ ] Yes
[ ] No

Other information

[griest024]

@xelaint I've pushed some changes that should generate the design docs as you need. LMK if not.

[griest024]

some links in the design readme are wrong. The link generation logic does not check to see if the referenced doc exists, so bad links won't be caught during docsgen