docs(okf): FROG - docs lint table padding and spellcheck frontmatter gotchas

Two docs-lint traps hit while authoring a migration guide, neither
discoverable from the scripts themselves.

lint:markdown has no --fix variant and no allowlisted formatter for
docs/**, so wide markdown tables are hand-aligned by trial and error.
Record the {/* prettier-ignore */} pattern v26 already uses.

lint:spellcheck exits 0 when it cannot parse a page's YAML frontmatter,
silently skipping it, so a green exit code does not mean the frontmatter
was checked.