docs: fix all rustdoc warnings (#1474)

tokio-io/src/async_read.rs

@@ -59,7 +59,7 @@ pub trait AsyncRead {
     ///
     /// This function is called from [`poll_read_buf`].
     ///
-    /// [`io::Read`]: https://doc.rust-lang.org/std/io/trait.Read.html
+    /// [`io::Read`]: std::io::Read
     /// [`poll_read_buf`]: #method.poll_read_buf
     unsafe fn prepare_uninitialized_buffer(&self, buf: &mut [u8]) -> bool {
         for x in buf {

tokio-io/src/io/buf_reader.rs

@@ -22,9 +22,6 @@ use std::{cmp, fmt};
 /// When the `BufReader` is dropped, the contents of its buffer will be
 /// discarded. Creating multiple instances of a `BufReader` on the same
 /// stream can cause data loss.
-///
-/// [`AsyncRead`]: tokio_io::AsyncRead
-///
 // TODO: Examples
 pub struct BufReader<R> {
     inner: R,

tokio-io/src/io/buf_writer.rs

@@ -24,7 +24,7 @@ use std::task::{Context, Poll};
 /// stream can cause data loss. If you need to write out the contents of its
 /// buffer, you must manually call flush before the writer is dropped.
 ///
-/// [`AsyncWrite`]: tokio_io::AsyncWrite
+/// [`AsyncWrite`]: AsyncWrite
 /// [`flush`]: super::AsyncWriteExt::flush
 ///
 // TODO: Examples

tokio-io/src/io/flush.rs

@@ -7,8 +7,6 @@ use std::task::{Context, Poll};
 /// A future used to fully flush an I/O object.
 ///
 /// Created by the [`AsyncWriteExt::flush`] function.
-///
-/// [`flush`]: fn.flush.html
 #[derive(Debug)]
 pub struct Flush<'a, A: ?Sized> {
     a: &'a mut A,

tokio-io/src/io/mod.rs

@@ -1,41 +1,3 @@
-//! Asynchronous I/O.
-//!
-//! This module is the asynchronous version of `std::io`. Primarily, it
-//! defines two traits, [`AsyncRead`] and [`AsyncWrite`], which extend the
-//! `Read` and `Write` traits of the standard library.
-//!
-//! # AsyncRead and AsyncWrite
-//!
-//! [`AsyncRead`] and [`AsyncWrite`] must only be implemented for
-//! non-blocking I/O types that integrate with the futures type system. In
-//! other words, these types must never block the thread, and instead the
-//! current task is notified when the I/O resource is ready.
-//!
-//! # Standard input and output
-//!
-//! Tokio provides asynchronous APIs to standard [input], [output], and [error].
-//! These APIs are very similar to the ones provided by `std`, but they also
-//! implement [`AsyncRead`] and [`AsyncWrite`].
-//!
-//! Unlike *most* other Tokio APIs, the standard input / output APIs
-//! **must** be used from the context of the Tokio runtime as they require
-//! Tokio specific features to function.
-//!
-//! [input]: fn.stdin.html
-//! [output]: fn.stdout.html
-//! [error]: fn.stderr.html
-//!
-//! # `std` re-exports
-//!
-//! Additionally, [`Error`], [`ErrorKind`], and [`Result`] are re-exported
-//! from `std::io` for ease of use.
-//!
-//! [`AsyncRead`]: trait.AsyncRead.html
-//! [`AsyncWrite`]: trait.AsyncWrite.html
-//! [`Error`]: struct.Error.html
-//! [`ErrorKind`]: enum.ErrorKind.html
-//! [`Result`]: type.Result.html
-
 mod async_buf_read_ext;
 mod async_read_ext;
 mod async_write_ext;

tokio-io/src/io/read_exact.rs

@@ -9,9 +9,7 @@ use std::task::{Context, Poll};
 /// A future which can be used to easily read exactly enough bytes to fill
 /// a buffer.
 ///
-/// Created by the [`read_exact`] function.
-///
-/// [`read_exact`]: fn.read_exact.html
+/// Created by the [`AsyncRead::read_exact`].
 pub(crate) fn read_exact<'a, A>(reader: &'a mut A, buf: &'a mut [u8]) -> ReadExact<'a, A>
 where
     A: AsyncRead + Unpin + ?Sized,

tokio-io/src/io/shutdown.rs

@@ -7,8 +7,6 @@ use std::task::{Context, Poll};
 /// A future used to shutdown an I/O object.
 ///
 /// Created by the [`AsyncWriteExt::shutdown`] function.
-///
-/// [`shutdown`]: fn.shutdown.html
 #[derive(Debug)]
 pub struct Shutdown<'a, A: ?Sized> {
     a: &'a mut A,