docs: fixing broken links in tokio/src/lib.rs
//! [`tokio::runtime`]: crate::runtime
//! [`Builder`]: crate::runtime::Builder
//! [`Runtime`]: crate::runtime::Runtime
-//! [rt]: runtime/index.html#basic-scheduler
-//! [rt-multi-thread]: runtime/index.html#threaded-scheduler
+//! [rt]: runtime/index.html#current-thread-scheduler
+//! [rt-multi-thread]: runtime/index.html#multi-thread-scheduler
//! [rt-features]: runtime/index.html#runtime-scheduler
//!
//! ## CPU-bound tasks and blocking code
