Document moved spec of timeval struct

src/header/sys_select/mod.rs

@@ -23,6 +23,10 @@ use crate::{
 
 /// See <https://pubs.opengroup.org/onlinepubs/9799919799/basedefs/sys_select.h.html>.
 ///
+/// Note that the `timeval` struct was specified for
+/// [`sys/time.h`](crate::header::sys_time) in the Open Group Base
+/// Specifications Issue 7 and prior, see
+/// <https://pubs.opengroup.org/onlinepubs/9699919799/basedefs/sys_time.h.html>.
 #[repr(C)]
 #[derive(Default)]
 pub struct timeval {

src/header/sys_time/mod.rs

@@ -1,6 +1,10 @@
 //! `sys/time.h` implementation.
 //!
 //! See <https://pubs.opengroup.org/onlinepubs/9799919799/basedefs/sys_time.h.html>.
+//!
+//! Note that since the Open Group Base Specifications Issue 8, the
+//! [`timeval`](crate::header::sys_select::timeval) struct has been moved to
+//! the [`sys/select.h`](crate::header::sys_select) header.
 
 use crate::{
     c_str::CStr,