a79249bbff
- traits.md: iterator.rs anchor L76→L42 (pub const trait Iterator) - traits.md: deref.rs anchor L60→L139 (pub const trait Deref) - error-handling.md: fix variant names CliError::Io→IoError, Parse→ParseError to match actual stdlib doc example at convert/mod.rs:557 - concurrency.md: mutex.rs and rwlock.rs moved to sync/poison/ subtree (3 link updates: mutex×2, rwlock×1)