chore: enforce 80-column Markdown prose wrapping

[arekay-nv]

What does this PR do?

Wrap Markdown prose at 80 columns with Prettier's proseWrap: always and
printWidth: 80, scoped to Markdown in .prettierrc.yaml. Long paragraphs
are automatically reflowed by the existing pre-commit hook; the existing
Pre-commit GitHub Actions workflow runs that same hook on all tracked files
and fails when formatting changes are needed.

Reformat the existing Markdown files so the rule can take effect immediately,
and document the policy and formatting command in the development guide and
agent instructions. Tables, code blocks, and indivisible links or inline code
may exceed the target width. This is a prose-wrapping policy, not a hard limit
on every Markdown source line.

Type of change

• Documentation update
• Refactor/cleanup

Testing

• Confirmed that overlong prose in .md and nested .markdown files fails
  the hook, is wrapped to at most 80 columns, and passes on the second run.
• Compared parsed Markdown structure, inline content, and code blocks for
  all 59 formatting-only files; no differences other than prose whitespace.
  The two files with intentional documentation additions were reviewed separately.
• git diff --check
• Ran uv run pre-commit run --all-files: all hooks passed except macOS
  mypy errors for Linux-only os.sched_setaffinity / os.sched_getaffinity
  in unchanged source files. Re-ran the same mypy environment with
  --platform linux (the CI platform): all 333 source files passed.

Checklist

• Code follows project style
• Documentation updated
• All pre-commit hooks pass with the local host platform (see macOS note above)

[github-actions]

MLCommons CLA bot All contributors have signed the MLCommons CLA ✍️ ✅