docs: replace some html links with rustdoc paths (#2381)

Included changes
- all simple references like `<type>.<name>.html` for these types
    - enum
    - fn
    - struct
    - trait
    - type
- simple references for methods, like struct.DelayQueue.html#method.poll

Refs: #1473

4 files changed, 17 insertions, 17 deletions

diff --git a/tokio/src/sync/mutex.rs b/tokio/src/sync/mutex.rs
index 6b51b405..7167906d 100644
--- a/tokio/src/sync/mutex.rs
+++ b/tokio/src/sync/mutex.rs
@@ -76,8 +76,8 @@
 //! case, the mutex will be unlocked. If the panic is caught, this might leave
 //! the data protected by the mutex in an inconsistent state.
 //!
-//! [`Mutex`]: struct.Mutex.html
-//! [`MutexGuard`]: struct.MutexGuard.html
+//! [`Mutex`]: struct@Mutex
+//! [`MutexGuard`]: struct@MutexGuard
 use crate::coop::CoopFutureExt;
 use crate::sync::batch_semaphore as semaphore;
 
diff --git a/tokio/src/sync/oneshot.rs b/tokio/src/sync/oneshot.rs
index 644832b9..62ad484e 100644
--- a/tokio/src/sync/oneshot.rs
+++ b/tokio/src/sync/oneshot.rs
@@ -16,7 +16,7 @@ use std::task::{Context, Poll, Waker};
 
 /// Sends a value to the associated `Receiver`.
 ///
-/// Instances are created by the [`channel`](fn.channel.html) function.
+/// Instances are created by the [`channel`](fn@channel) function.
 #[derive(Debug)]
 pub struct Sender<T> {
     inner: Option<Arc<Inner<T>>>,
@@ -24,7 +24,7 @@ pub struct Sender<T> {
 
 /// Receive a value from the associated `Sender`.
 ///
-/// Instances are created by the [`channel`](fn.channel.html) function.
+/// Instances are created by the [`channel`](fn@channel) function.
 #[derive(Debug)]
 pub struct Receiver<T> {
     inner: Option<Arc<Inner<T>>>,
diff --git a/tokio/src/sync/rwlock.rs b/tokio/src/sync/rwlock.rs
index 0f7991a5..68cf710e 100644
--- a/tokio/src/sync/rwlock.rs
+++ b/tokio/src/sync/rwlock.rs
@@ -62,10 +62,10 @@ const MAX_READS: usize = 10;
 /// }
 /// ```
 ///
-/// [`Mutex`]: struct.Mutex.html
-/// [`RwLock`]: struct.RwLock.html
-/// [`RwLockReadGuard`]: struct.RwLockReadGuard.html
-/// [`RwLockWriteGuard`]: struct.RwLockWriteGuard.html
+/// [`Mutex`]: struct@super::Mutex
+/// [`RwLock`]: struct@RwLock
+/// [`RwLockReadGuard`]: struct@RwLockReadGuard
+/// [`RwLockWriteGuard`]: struct@RwLockWriteGuard
 /// [`Send`]: https://doc.rust-lang.org/std/marker/trait.Send.html
 /// [_write-preferring_]: https://en.wikipedia.org/wiki/Readers%E2%80%93writer_lock#Priority_policies
 #[derive(Debug)]
@@ -83,7 +83,7 @@ pub struct RwLock<T> {
 /// This structure is created by the [`read`] method on
 /// [`RwLock`].
 ///
-/// [`read`]: struct.RwLock.html#method.read
+/// [`read`]: method@RwLock::read
 #[derive(Debug)]
 pub struct RwLockReadGuard<'a, T> {
     permit: ReleasingPermit<'a, T>,
@@ -96,8 +96,8 @@ pub struct RwLockReadGuard<'a, T> {
 /// This structure is created by the [`write`] and method
 /// on [`RwLock`].
 ///
-/// [`write`]: struct.RwLock.html#method.write
-/// [`RwLock`]: struct.RwLock.html
+/// [`write`]: method@RwLock::write
+/// [`RwLock`]: struct@RwLock
 #[derive(Debug)]
 pub struct RwLockWriteGuard<'a, T> {
     permit: ReleasingPermit<'a, T>,
diff --git a/tokio/src/sync/watch.rs b/tokio/src/sync/watch.rs
index 402670f4..ba609a8c 100644
--- a/tokio/src/sync/watch.rs
+++ b/tokio/src/sync/watch.rs
@@ -62,9 +62,9 @@ use std::sync::{Arc, Mutex, RwLock, RwLockReadGuard, Weak};
 use std::task::Poll::{Pending, Ready};
 use std::task::{Context, Poll};
 
-/// Receives values from the associated [`Sender`](struct.Sender.html).
+/// Receives values from the associated [`Sender`](struct@Sender).
 ///
-/// Instances are created by the [`channel`](fn.channel.html) function.
+/// Instances are created by the [`channel`](fn@channel) function.
 #[derive(Debug)]
 pub struct Receiver<T> {
     /// Pointer to the shared state
@@ -74,9 +74,9 @@ pub struct Receiver<T> {
     inner: Watcher,
 }
 
-/// Sends values to the associated [`Receiver`](struct.Receiver.html).
+/// Sends values to the associated [`Receiver`](struct@Receiver).
 ///
-/// Instances are created by the [`channel`](fn.channel.html) function.
+/// Instances are created by the [`channel`](fn@channel) function.
 #[derive(Debug)]
 pub struct Sender<T> {
     shared: Weak<Shared<T>>,
@@ -172,8 +172,8 @@ const CLOSED: usize = 1;
 /// # }
 /// ```
 ///
-/// [`Sender`]: struct.Sender.html
-/// [`Receiver`]: struct.Receiver.html
+/// [`Sender`]: struct@Sender
+/// [`Receiver`]: struct@Receiver
 pub fn channel<T: Clone>(init: T) -> (Sender<T>, Receiver<T>) {
     const VERSION_0: usize = 0;
     const VERSION_1: usize = 2;