gh-138307: Update the Ellipsis documentation (#138306)

* Doc: Change Ellipsis doc at library/constants

* Doc: Change Ellipsis doc at library/stdtypes

* Doc: Add NumPy reference into Ellipsis doc at library/stdtypes

* Doc: Add Ellipsis reference into the pass statement section at tutorial

* Doc: Update Ellipsis doc concerns assignments at library/constants

* Update Doc/library/stdtypes.rst

Co-authored-by: Stan Ulbrych <89152624+StanFromIreland@users.noreply.github.com>

* Doc: Fix grammar on Ellipsis docs (library/constants.rst)

Co-authored-by: Éric <merwok@netwok.org>

* Doc: Fix grammar on Ellipsis docs (library/stdtypes.rst)

Co-authored-by: Éric <merwok@netwok.org>

* Doc: Fix grammar on Ellipsis docs (library/stdtypes.rst)

Co-authored-by: Éric <merwok@netwok.org>

* Doc: Remove pretty printers reference from Ellipsis doc at library/stdtypes

* Doc: Update index concerns Ellipsis object and pass statement

* Doc: Improve Ellipsis doc at library/constants

* Doc: Improve Ellipsis doc at library/stdtypes

* Doc: Change the "..." glossary entry to mention the Ellipsis object

* Doc: Some improvements concern ellipsis into typing doc

* Minor update Doc/tutorial/controlflow.rst

Co-authored-by: Ned Batchelder <ned@nedbatchelder.com>

* Update Doc/library/constants.rst

Co-authored-by: Ned Batchelder <ned@nedbatchelder.com>

* Update Doc/library/stdtypes.rst

Co-authored-by: Ned Batchelder <ned@nedbatchelder.com>

---------

Co-authored-by: Stan Ulbrych <89152624+StanFromIreland@users.noreply.github.com>
Co-authored-by: Éric <merwok@netwok.org>
Co-authored-by: Ned Batchelder <ned@nedbatchelder.com>