doc: fix some links (#2834)

tokio/src/io/util/async_read_ext.rs

@@ -1067,7 +1067,7 @@ cfg_io_util! {
         /// (See also the [`crate::fs::read_to_string`] convenience function for
         /// reading from a file.)
         ///
-        /// [`crate::fs::read_to_string`]: crate::fs::read_to_string::read_to_string
+        /// [`crate::fs::read_to_string`]: fn@crate::fs::read_to_string
         fn read_to_string<'a>(&'a mut self, dst: &'a mut String) -> ReadToString<'a, Self>
         where
             Self: Unpin,

tokio/src/net/udp/socket.rs

@@ -125,7 +125,7 @@ impl UdpSocket {
     /// should ensure that when the remote cannot receive, the
     /// [`ErrorKind::WouldBlock`] is properly handled.
     ///
-    /// [`ErrorKind::WouldBlock`]: std::io::error::ErrorKind::WouldBlock
+    /// [`ErrorKind::WouldBlock`]: std::io::ErrorKind::WouldBlock
     pub fn try_send(&self, buf: &[u8]) -> io::Result<usize> {
         self.io.get_ref().send(buf)
     }
@@ -209,7 +209,7 @@ impl UdpSocket {
     /// [`ErrorKind::WouldBlock`] is properly handled. An error can also occur
     /// if the IP version of the socket does not match that of `target`.
     ///
-    /// [`ErrorKind::WouldBlock`]: std::io::error::ErrorKind::WouldBlock
+    /// [`ErrorKind::WouldBlock`]: std::io::ErrorKind::WouldBlock
     pub fn try_send_to(&self, buf: &[u8], target: SocketAddr) -> io::Result<usize> {
         self.io.get_ref().send_to(buf, &target)
     }

tokio/src/sync/mod.rs

@@ -397,8 +397,8 @@
 //! }
 //! ```
 //!
-//! [`watch` channel]: crate::sync::watch
-//! [`broadcast` channel]: crate::sync::broadcast
+//! [`watch` channel]: mod@crate::sync::watch
+//! [`broadcast` channel]: mod@crate::sync::broadcast
 //!
 //! # State synchronization
 //!