io/ioutil: add doc links for deprecated function

Go1.19 introduced [doc link](https://go.dev/doc/comment#doclinks), It
will be convenient when we can directly jump to the suggested function
when the original function is deprecated.

Author: SilverRainZ

src/io/ioutil/ioutil.go

@@ -5,7 +5,7 @@
 // Package ioutil implements some I/O utility functions.
 //
 // Deprecated: As of Go 1.16, the same functionality is now provided
-// by package io or package os, and those implementations
+// by package [io] or package [os], and those implementations
 // should be preferred in new code.
 // See the specific function documentation for details.
 package ioutil
@@ -22,7 +22,7 @@ import (
 // defined to read from src until EOF, it does not treat an EOF from Read
 // as an error to be reported.
 //
-// Deprecated: As of Go 1.16, this function simply calls io.ReadAll.
+// Deprecated: As of Go 1.16, this function simply calls [io.ReadAll].
 func ReadAll(r io.Reader) ([]byte, error) {
 	return io.ReadAll(r)
 }
@@ -32,7 +32,7 @@ func ReadAll(r io.Reader) ([]byte, error) {
 // reads the whole file, it does not treat an EOF from Read as an error
 // to be reported.
 //
-// Deprecated: As of Go 1.16, this function simply calls os.ReadFile.
+// Deprecated: As of Go 1.16, this function simply calls [os.ReadFile].
 func ReadFile(filename string) ([]byte, error) {
 	return os.ReadFile(filename)
 }
@@ -41,7 +41,7 @@ func ReadFile(filename string) ([]byte, error) {
 // If the file does not exist, WriteFile creates it with permissions perm
 // (before umask); otherwise WriteFile truncates it before writing, without changing permissions.
 //
-// Deprecated: As of Go 1.16, this function simply calls os.WriteFile.
+// Deprecated: As of Go 1.16, this function simply calls [os.WriteFile].
 func WriteFile(filename string, data []byte, perm fs.FileMode) error {
 	return os.WriteFile(filename, data, perm)
 }
@@ -51,12 +51,12 @@ func WriteFile(filename string, data []byte, perm fs.FileMode) error {
 // sorted by filename. If an error occurs reading the directory,
 // ReadDir returns no directory entries along with the error.
 //
-// Deprecated: As of Go 1.16, os.ReadDir is a more efficient and correct choice:
-// it returns a list of fs.DirEntry instead of fs.FileInfo,
+// Deprecated: As of Go 1.16, [os.ReadDir] is a more efficient and correct choice:
+// it returns a list of [fs.DirEntry] instead of [fs.FileInfo],
 // and it returns partial results in the case of an error
 // midway through reading a directory.
 //
-// If you must continue obtaining a list of fs.FileInfo, you still can:
+// If you must continue obtaining a list of [fs.FileInfo], you still can:
 //
 //	entries, err := os.ReadDir(dirname)
 //	if err != nil { ... }
@@ -83,13 +83,13 @@ func ReadDir(dirname string) ([]fs.FileInfo, error) {
 // NopCloser returns a ReadCloser with a no-op Close method wrapping
 // the provided Reader r.
 //
-// Deprecated: As of Go 1.16, this function simply calls io.NopCloser.
+// Deprecated: As of Go 1.16, this function simply calls [io.NopCloser].
 func NopCloser(r io.Reader) io.ReadCloser {
 	return io.NopCloser(r)
 }
 
 // Discard is an io.Writer on which all Write calls succeed
 // without doing anything.
 //
-// Deprecated: As of Go 1.16, this value is simply io.Discard.
+// Deprecated: As of Go 1.16, this value is simply [io.Discard].
 var Discard io.Writer = io.Discard

src/io/ioutil/tempfile.go

@@ -20,7 +20,7 @@ import (
 // to find the pathname of the file. It is the caller's responsibility
 // to remove the file when no longer needed.
 //
-// Deprecated: As of Go 1.17, this function simply calls os.CreateTemp.
+// Deprecated: As of Go 1.17, this function simply calls [os.CreateTemp].
 func TempFile(dir, pattern string) (f *os.File, err error) {
 	return os.CreateTemp(dir, pattern)
 }
@@ -35,7 +35,7 @@ func TempFile(dir, pattern string) (f *os.File, err error) {
 // will not choose the same directory. It is the caller's responsibility
 // to remove the directory when no longer needed.
 //
-// Deprecated: As of Go 1.17, this function simply calls os.MkdirTemp.
+// Deprecated: As of Go 1.17, this function simply calls [os.MkdirTemp].
 func TempDir(dir, pattern string) (name string, err error) {
 	return os.MkdirTemp(dir, pattern)
 }