Fallout from the removal of `doc_auto_cfg`

[sunipkm]

I am on rustc v1.91.0, and encountering

   --> heapless-0.9.1/src/lib.rs:133:47
    |
133 | #![cfg_attr(docsrs, feature(doc_cfg), feature(doc_auto_cfg))]
    |                                               ^^^^^^^^^^^^ feature has been removed
    |
    = note: removed in CURRENT_RUSTC_VERSION; see <https://github.com/rust-lang/rust/pull/138907> for more information
    = note: merged into `doc_cfg`

[sgued]

Are you using --cfg docsrs ? This shouldn't be used.

[burrbull]

doc_auto_cfg is renamed to doc_cfg

[sunipkm]

Are you using --cfg docsrs ? This shouldn't be used.

Yes, I was compiling docs for my crate that uses heapless, and I have some feature flags...

[sgued]

Oh I see, this might also be a painpoint for downstreams that are using --cfg docsrs for documentation too. We need to release 0.9.2 for that. I think we can aim for a release soon.