Remove `feature(external_doc)` completely
)]
#![allow(clippy::match_bool)]
#![forbid(unsafe_code)]
-#![cfg_attr(all(feature = "nightly", doctest), feature(external_doc))]
#![cfg_attr(feature = "nightly", feature(doc_cfg))]
// we pass "--cfg docsrs" when building docs to add `This is supported on
