Fix a broken link in a doc comment.

Author: sunfishcode

src/runtime/mod.rs

@@ -2,7 +2,7 @@
 //!
 //! The way to use this is to call [`block_on()`]. Inside the future, [`Reactor::current`]
 //! will give an instance of the [`Reactor`] running the event loop, which can be
-//! to [`Reactor::wait_for`] instances of
+//! to [`AsyncPollable::wait_for`] instances of
 //! [`wasi::Pollable`](https://docs.rs/wasi/latest/wasi/io/poll/struct.Pollable.html).
 //! This will automatically wait for the futures to resolve, and call the
 //! necessary wakers to work.