Improve documentation for Box::into_inner

[ZhangHanDong]

cc #80437

Signed-off-by: blackanger <bl Improve documentation for Box::into_inner #98523 ackanger.z@gmail.com>

Blocked on tracking issue comment

[rust-highfive]

Hey! It looks like you've submitted a new PR for the library teams!

If this PR contains changes to any rust-lang/rust public library APIs then please comment with @rustbot label +T-libs-api -T-libs to tag it appropriately. If this PR contains changes to any unstable APIs please edit the PR description to add a link to the relevant API Change Proposal or create one if you haven't already. If you're unsure where your change falls no worries, just leave it as is and the reviewer will take a look and make a decision to forward on if necessary.

Examples of T-libs-api changes:

• Stabilizing library features
• Introducing insta-stable changes such as new implementations of existing stable traits on existing stable types
• Introducing new or changing existing unstable library APIs (excluding permanently unstable features / features without a tracking issue)
• Changing public documentation in ways that create new stability guarantees
• Changing observable runtime behavior of library APIs

[rust-highfive]

Thanks for the pull request, and welcome! The Rust team is excited to review your changes, and you should hear from @Mark-Simulacrum (or someone else) soon.

Please see the contribution instructions for more information.

[crlf0710]

ci still red
r? @dtolnay
@rustbot author

[ZhangHanDong]

@rustbot ready

[dtolnay]

@rustbot blocked. #80437 (comment)

[dtolnay]

Closing in favor of ongoing discussion in #80437. It seems we don't really have a clear picture what this method is for, and the example here isn't compelling to me. If anyone in #80437 lands on a better example, I'd be happy about a PR for it, otherwise we'll hopefully be removing this method.

Thanks anyway for the contribution!