*: Use auto_doc_cfg instead of doc(cfg) attributes (#2983)

Co-authored-by: João Oliveira <hello@jxs.pt>
Co-authored-by: Thomas Eizinger <thomas@eizinger.io>

protocols/gossipsub/src/lib.rs

@@ -133,6 +133,8 @@
 //! println!("Listening on {:?}", addr);
 //! ```
 
+#![cfg_attr(docsrs, feature(doc_cfg, doc_auto_cfg))]
+
 pub mod error;
 pub mod protocol;