[3.14] gh-130160: use `.. program::` directive for documenting `venv` CLI (GH-130699) (#136550)

gh-130160: use `.. program::` directive for documenting `venv` CLI (GH-130699)
(cherry picked from commit fb9f933b8eda6cdc1336582dc8709b759ced91af)

Co-authored-by: Kanishk Pachauri <itskanishkp.py@gmail.com>
Co-authored-by: Semyon Moroz <donbarbos@proton.me>
Co-authored-by: Bénédikt Tran <10796600+picnixz@users.noreply.github.com>