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>

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(cherry picked from commit 41ef502d740b96ca6333a2d0202df7cce4a84e7d)

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>