generate docs for feature gated items (#1332)

* generate docs for feature-gated items on crates.io

* add newline in Cargo.toml

* unify newlines

* fix clippy

* introduce macros for features

* commit missing file

* Update subxt/src/lib.rs

* make it compile

lightclient/Cargo.toml

@@ -80,3 +80,10 @@ pin-project = { workspace = true, optional = true }
 
 # Included if "web" feature is enabled, to enable its js feature.
 getrandom = { workspace = true, optional = true }
+
+[package.metadata.docs.rs]
+defalt-features = true
+rustdoc-args = ["--cfg", "docsrs"]
+
+[package.metadata.playground]
+defalt-features = true

lightclient/src/lib.rs

@@ -10,6 +10,8 @@
 //!
 //! This leverages the smoldot crate to connect to the chain.
 
+#![cfg_attr(docsrs, feature(doc_cfg))]
+
 #[cfg(any(
     all(feature = "web", feature = "native"),
     not(any(feature = "web", feature = "native"))
@@ -35,6 +37,7 @@ pub mod smoldot {
     };
 
     #[cfg(feature = "native")]
+    #[cfg_attr(docsrs, doc(cfg(feature = "native")))]
     pub use smoldot_light::platform::default::DefaultPlatform;
 }