frankenphp

24be6681 - docs: add SEO frontmatter, llms.txt, and code-block hygiene (#2394)

docs: add SEO frontmatter, llms.txt, and code-block hygiene (#2394) ## Summary - Adds YAML frontmatter (`title`, `description`) to every English doc under `docs/*.md` for SEO and LLM/RAG ingestion. - Renames generic headings (`## Setup`, `## Configuration`, etc.) to topic-specific ones; updates the one inbound cross-link affected by an anchor rename. - Tightens code blocks: language tags fixed where wrong (e.g. `console` → `bash`, `caddy` → `caddyfile`), and a first-line filename or purpose comment added on blocks that represent a real file. - Adds a root `llms.txt` index pointing AI agents at the canonical English docs (Core Concepts, Setup and Build, Worker Mode and Extensions, Frameworks, Real-Time and Performance, Production and Observability). ## Notes - Translations under `docs/<lang>/` are intentionally untouched. Re-run `docs/translate.php` after merge to propagate the new frontmatter and renamed headings. - Anchor renames are scoped to genuinely generic headings; already-specific ones were left alone.