gh-131912: Use different grouping options for the integral and fractional parts

[Prometheus3375]

A small addition to #132030 discussed in #132123. There are many examples with _ used as digit group separator, but only one with ,. I changed last two examples with floating-point number to include a comma separator. I believe it is sufficient to show that both options can be used for both integral and fractional parts, as well as the fact that a user can mix them.

• Issue: Move description of grouping options in format specification docs #131912

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📚 Documentation preview 📚

[Prometheus3375]

It is a bit weird that only in the first example format string is rendered in bold. As if all others are not recognized by the renderer as a valid format.

[skirpichev]

It is a bit weird that only in the first example format string is rendered in bold.

Looks as a sphinx bug. @picnixz ?

[Prometheus3375]

This one shouldn't be backported as 3.13 and below do not have grouping for fractional part.

[picnixz]

Looks as a sphinx bug

That would be a Pygment issue in this case. Sphinx delegates highlighting to pygments.

[skirpichev]

Ah, indeed. Thanks.

The problem might be reported, see pygments/pygments#1340. Though, maybe it's a slightly different one. @Prometheus3375 would you like to investigate it and report to upstream?

[Prometheus3375]

Looks to me as the same. I will provide an additional context in that issue.

[skirpichev]

It might be different just because '_' separators were introduced in formatting mini-language later. Just a guess.

[Prometheus3375]

They were introduced quite a while ago, in 3.6. Nethertheless, it is not the only place where highlighting does not occur. The same happens in a couple examples below like date format and nested formatting.