[Catalog-sig] Syntax highlighting for code examples on PyPI

[Éric Araujo]

> Also for C code examples which some PyPI packages use.
Good point.

> I don't think "sphinx style" *precludes* specifying the language though?
Depends what you mean by that.  The Shinx-provided code-block directive
takes an argument, so it’s good, but the implicit style (using a syntax
code block introduced by “::”, not a directive) does not TTBOMK.

Regards