Remove rustdoc warnings for core::features
Remove rustdoc warnings for core::features

Link `CliUnstable::add` just to `CliUnstable` instead.

Signed-off-by: Paul Mabileau <a3aedf8c87c1af3dfeae5f57ddf6d5ae82ad981f@hotmail.fr>

rustyhorde/cargo,rust-lang/cargo,rust-lang/cargo,eminence/cargo,rust-lang/cargo,rustyhorde/cargo,rustyhorde/cargo,rustyhorde/cargo,nipunn1313/cargo,rust-lang/cargo,eminence/cargo,nipunn1313/cargo,nipunn1313/cargo,eminence/cargo,nipunn1313/cargo,eminence/cargo