doc(fs): fix broken links

Author: Berrysoft

compio-fs/src/stdio/unix.rs

@@ -4,6 +4,8 @@ use compio_buf::{BufResult, IoBuf, IoBufMut, IoVectoredBuf, IoVectoredBufMut};
 use compio_driver::{AsRawFd, FromRawFd, RawFd};
 use compio_io::{AsyncRead, AsyncWrite};
 
+#[cfg(doc)]
+use super::{stderr, stdin, stdout};
 use crate::pipe::{Receiver, Sender};
 
 /// A handle to the standard input stream of a process.

compio-fs/src/stdio/windows.rs

@@ -15,6 +15,9 @@ use compio_io::{AsyncRead, AsyncWrite};
 use compio_runtime::Runtime;
 use windows_sys::Win32::System::IO::OVERLAPPED;
 
+#[cfg(doc)]
+use super::{stderr, stdin, stdout};
+
 struct StdRead<R: Read, B: IoBufMut> {
     reader: R,
     buffer: B,