docs: minor fix in tcgetpgrp and tcsetpgrp doc comments (#2731)

* docs: minor fix in tcgetpgrp and tcsetpgrp doc comments

mistakes fixed:
* Used GPID instead of PGID in tcgetpgrp comment.
* Used 'Get' instead of 'Set' in tcsetpgrp comment.

* docs: group process id -> process group id

* docs: group process id -> process group id

---------

Co-authored-by: SteveLauC <stevelauc@outlook.com>

Author: rajeshrah22

src/unistd.rs

@@ -353,7 +353,7 @@ feature! {
 /// Get the terminal foreground process group (see
 /// [tcgetpgrp(3)](https://pubs.opengroup.org/onlinepubs/9699919799/functions/tcgetpgrp.html)).
 ///
-/// Get the group process id (GPID) of the foreground process group on the
+/// Get the process group id (PGID) of the foreground process group on the
 /// terminal associated to file descriptor (FD).
 #[inline]
 pub fn tcgetpgrp<F: std::os::fd::AsFd>(fd: F) -> Result<Pid> {
@@ -363,9 +363,9 @@ pub fn tcgetpgrp<F: std::os::fd::AsFd>(fd: F) -> Result<Pid> {
     Errno::result(res).map(Pid)
 }
 /// Set the terminal foreground process group (see
-/// [tcgetpgrp(3)](https://pubs.opengroup.org/onlinepubs/9699919799/functions/tcsetpgrp.html)).
+/// [tcsetpgrp(3)](https://pubs.opengroup.org/onlinepubs/9699919799/functions/tcsetpgrp.html)).
 ///
-/// Get the group process id (PGID) to the foreground process group on the
+/// Set the process group id (PGID) to the foreground process group on the
 /// terminal associated to file descriptor (FD).
 #[inline]
 pub fn tcsetpgrp<F: std::os::fd::AsFd>(fd: F, pgrp: Pid) -> Result<()> {