replace use of doc_auto_cfg, doc_cfg_hide features with doc_cfg

[iamjpotts]

Resolves this error, which started with nightly-2025-09-28 (current nightly). The error does not reproduce on nightly-2025-09-27.

RUSTDOCFLAGS='-Dwarnings --cfg=docsrs' cargo doc --document-private-items
 Documenting deranged v0.5.4 (./deranged/deranged)
error[E0557]: feature has been removed
 --> deranged/src/lib.rs:3:29
  |
3 | #![cfg_attr(docsrs, feature(doc_auto_cfg, doc_cfg_hide))]
  |                             ^^^^^^^^^^^^ feature has been removed
  |
  = note: removed in 1.58.0; see <https://github.com/rust-lang/rust/pull/138907> for more information
  = note: merged into `doc_cfg`

error[E0557]: feature has been removed
 --> deranged/src/lib.rs:3:43
  |
3 | #![cfg_attr(docsrs, feature(doc_auto_cfg, doc_cfg_hide))]
  |                                           ^^^^^^^^^^^^ feature has been removed
  |
  = note: removed in 1.57.0; see <https://github.com/rust-lang/rust/pull/138907> for more information
  = note: merged into `doc_cfg`

error: Compilation failed, aborting rustdoc

For more information about this error, try `rustc --explain E0557`.
error: could not document `deranged`

PR linked in error message:
rust-lang/rust#138907

Similar change made to rattatui in last few hours:
ratatui/ratatui#2103

[jhpratt]

While this PR is trivial, I don't have the time to handle this and other crates at the moment. I'm surprised that this is an error and not a warning, though.

[robamu]

It is a bit unfortunate that this is an error. It propagates to the documentation build of a lot of other crates unfortunately (through the time crate in my case)

[jhpratt]

Until I have the time to handle this, the simplest solution is to simply not pass --cfg docsrs.

[robamu]

For local builds, this works. But the docs.rs builds will probably fail if any dependency uses the obsolete feature.

UPDATE: I do not think this is an issue for docs.rs builds. They simply refer to the already built documentation of released creates/