fs: small documentation fixes (#3133)

tokio/src/fs/copy.rs

@@ -1,10 +1,13 @@
 use crate::fs::asyncify;
 use std::path::Path;
 
-/// Copies the contents of one file to another. This function will also copy the permission bits of the original file to the destination file.
+/// Copies the contents of one file to another. This function will also copy the permission bits
+/// of the original file to the destination file.
 /// This function will overwrite the contents of to.
 ///
-/// This is the async equivalent of `std::fs::copy`.
+/// This is the async equivalent of [`std::fs::copy`][std].
+///
+/// [std]: fn@std::fs::copy
 ///
 /// # Examples
 ///

tokio/src/fs/mod.rs

@@ -22,7 +22,7 @@
 //! `std::io::ErrorKind::WouldBlock` if a *worker* thread can not be converted
 //! to a *backup* thread immediately.
 //!
-//! [`AsyncRead`]: https://docs.rs/tokio-io/0.1/tokio_io/trait.AsyncRead.html
+//! [`AsyncRead`]: trait@crate::io::AsyncRead
 
 mod canonicalize;
 pub use self::canonicalize::canonicalize;

tokio/src/fs/read_to_string.rs

@@ -5,7 +5,9 @@ use std::{io, path::Path};
 /// Creates a future which will open a file for reading and read the entire
 /// contents into a string and return said string.
 ///
-/// This is the async equivalent of `std::fs::read_to_string`.
+/// This is the async equivalent of [`std::fs::read_to_string`][std].
+///
+/// [std]: fn@std::fs::read_to_string
 ///
 /// # Examples
 ///

tokio/src/fs/write.rs

@@ -5,7 +5,9 @@ use std::{io, path::Path};
 /// Creates a future that will open a file for writing and write the entire
 /// contents of `contents` to it.
 ///
-/// This is the async equivalent of `std::fs::write`.
+/// This is the async equivalent of [`std::fs::write`][std].
+///
+/// [std]: fn@std::fs::write
 ///
 /// # Examples
 ///