Enable all-features, Use doc_auto_cfg on docs.rs

- Display functions that are limited by feature, list feature required

Cargo.toml

@@ -39,3 +39,7 @@ zlib-ng = ["any_zlib", "libz-ng-sys"]
 cloudflare_zlib = ["any_zlib", "cloudflare-zlib-sys"]
 rust_backend = ["miniz_oxide"]
 miniz-sys = ["rust_backend"] # For backwards compatibility
+
+[package.metadata.docs.rs]
+all-features = true
+rustdoc-args = ["--cfg", "docsrs"]

src/lib.rs

@@ -76,6 +76,7 @@
 #![deny(missing_debug_implementations)]
 #![allow(trivial_numeric_casts)]
 #![cfg_attr(test, deny(warnings))]
+#![cfg_attr(docsrs, feature(doc_auto_cfg))]
 
 pub use crate::crc::{Crc, CrcReader, CrcWriter};
 pub use crate::gz::GzBuilder;