gh-127833: Docs: Add a `grammar-snippet` directive & replace `productionlist`#127835

Merged

encukou merged 20 commits intopython:mainfrom encukou:doc-grammar-snippets

Feb 5, 2025

+226-2

Commits on Nov 20, 2024

First version of GrammarSnippetDirective, copied from an earlier branch

committed

Commits on Dec 4, 2024