Function builtin_topics 

pub fn builtin_topics() -> HelpTopicRegistry

The built-in topic set, generated at build time by build.rs from every docs/user/**/*.md (recursively, skipping tutor/). Each doc’s --- YAML frontmatter supplies summary + related (see the build script); bodies are embedded as string literals so the binary stays self-contained — no runtime filesystem dependency. Adding a doc requires no change here: drop the .md into docs/user/ and it registers automatically. CR.1: returns the registry by value. The caller wraps it in a HelpTopicRegistryHandle via HelpTopicRegistry::into_handle — the builtin set is the initial contents of a runtime-writable registry now, not the whole of it.