[3.12] Doc: cmdline.rst: Include -P and -R in usage (GH-122590) (#122784)

Doc: cmdline.rst: Include -P and -R in usage (GH-122590)

* ``-P``: safe path (https://docs.python.org/3/using/cmdline.htmlGH-cmdoption-P)
* ``-R``: hash randomization (https://docs.python.org/3/using/cmdline.htmlGH-cmdoption-R)
(cherry picked from commit c25898d51e4ec84319b7113d5bf453c6e6519d9c)

Co-authored-by: Wim Jeantine-Glenn <hey@wimglenn.com>