unstable facade around the pin submodule

Signed-off-by: Yoshua Wuyts <[email protected]>

Author: yoshuawuyts

src/lib.rs

@@ -37,10 +37,12 @@ pub mod future;
 pub mod io;
 pub mod net;
 pub mod os;
-pub mod pin;
 pub mod prelude;
 pub mod stream;
 pub mod sync;
 pub mod task;
 
+#[cfg_attr(feature = "docs", doc(cfg(unstable)))]
+pub mod pin;
+
 pub(crate) mod utils;