Improve module description for std::f32 and std::f64

[palango]

Fixes #29353, see discussion there.

[rust-highfive]

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[BurntSushi]

@palango Thanks!

I'm not quite sure the docs here are enough to satisfy #29329.

It might be worth saying more about the distinction of constants defined in std::{f32,f64} and std::{f32,f64}::consts. For example, something like, "constants in this module are specific to the floating point implementation while constants in the consts sub-module contain mathematically significant numbers."

cc @steveklabnik @rust-lang/libs

[frewsxcv]

I think this URL should just be:

...provided in the [`consts`][consts] module.

or better yet:

...provided in the [`consts`] module.

[`consts`]: consts

[palango]

Thanks for the hint.

[palango]

@BurntSushi Thanks for your comments. I updated the description and think it's clearer now.

[palango]

Ok, I need some tips for getting the links to work.

If the link is done with [consts]: consts then I get the following error:

[00:43:58] std/f32/index.html:54: directory link - std/f32/consts
[00:43:58] std/index.html:452: broken link - std/consts
[00:43:58] std/index.html:462: broken link - std/consts
[00:44:00] std/f64/index.html:54: directory link - std/f64/consts

If I use [consts]: {f32|f64}/consts I get the following output, but one of of both always seems to be wrong.

[00:42:03] std/f32/index.html:54: broken link - std/f32/f32/consts
[00:42:03] std/index.html:452: directory link - std/f32/consts
[00:42:03] std/index.html:462: directory link - std/f64/consts
[00:42:05] std/f64/index.html:54: broken link - std/f64/f64/consts

[frewsxcv]

Ah, this is an example where linking doesn't always work. It looks like these links get rendered on different pages that live at different levels of the URL hierarchy. We're working on fixing this and making this easier in the future. Sorry for the confusion here, you can just remove the links for now @palango. Thanks for being patient! :)

[frewsxcv]

Thanks! @bors r+ rollup

[bors]

📌 Commit 4b4b1e1 has been approved by frewsxcv

[bors]

⌛ Testing commit 4b4b1e1 with merge 5637ed7...

[bors]

☀️ Test successful - status-appveyor, status-travis
Approved by: frewsxcv
Pushing 5637ed7 to master...