Add Doc section in free-threaded ext howto for critical sections#132531

Merged

nascheme merged 3 commits intopython:mainfrom

nascheme:critical-section-howto

Apr 16, 2025

Commits on Apr 14, 2025

Add section for critical sections to howto.
nascheme
committed

Commits on Apr 15, 2025

Improvements based on review feedback.
nascheme
committed

Commits on Apr 16, 2025

Fix markup.
nascheme
committed