Add link to sys.exit function documentation (GH-102805)

* Add link to `sys.exit` function documentation

* Update Doc/library/os.rst

Co-authored-by: Ezio Melotti <ezio.melotti@gmail.com>

* Update Doc/library/os.rst

Co-authored-by: C.A.M. Gerlach <CAM.Gerlach@Gerlach.CAM>

---------

(cherry picked from commit 41ef502)

Co-authored-by: David Poirier <1152277+david-poirier@users.noreply.github.com>
Co-authored-by: Ezio Melotti <ezio.melotti@gmail.com>
Co-authored-by: C.A.M. Gerlach <CAM.Gerlach@Gerlach.CAM>

Author: 4 people

Doc/library/os.rst

@@ -3658,7 +3658,7 @@ to be ignored.
 
    .. note::
 
-      The standard way to exit is ``sys.exit(n)``.  :func:`_exit` should
+      The standard way to exit is :func:`sys.exit(n) <sys.exit>`.  :func:`!_exit` should
       normally only be used in the child process after a :func:`fork`.
 
 The following exit codes are defined and can be used with :func:`_exit`,