quoted

I've not understood how to get rid of that colon, and I would prefer to leave the
explanation _after_ the corresponding code block, and not move it before.

https://www.sphinx-doc.org/en/master/usage/restructuredtext/basics.html#literal-blocks

This suggests that if you write it as "what follows is a button ::"
(i.e. space before ::) that should render it without a colon.

[...]

I.e. RTFM :(

Apologize for this; I'm going to send v3 with the space before ::.

Thank you,

Marco