Migrate all 17 docs/content/ files from --- YAML to +++ TOML
frontmatter delimiters and key = value syntax.
Update 8 embedded frontmatter examples in 7 documentation pages
to match (configuration, content-organization, getting-started,
security, sections, sitemap, feeds, templates).
Update configuration.md frontmatter reference table: add draft
and aliases fields, correct date type from string to date.
