Improve doc of RemoteChild

Signed-off-by: Jiahao XU <[email protected]>

Author: NobodyXu

src/child.rs

@@ -62,6 +62,9 @@ macro_rules! delegate {
 /// available,`Stdio::piped()` should be passed to the corresponding method on
 /// [`Command`](crate::Command).
 ///
+/// NOTE that once `RemoteChild` is dropped, any data written to `stdin` will not be send to the
+/// remote process and `stdout` and `stderr` would eof immediately.
+///
 /// ```rust,no_run
 /// # async fn foo() {
 /// # let child: openssh::RemoteChild<'static> = unimplemented!();